how to make my portraits more accurate?

I want to get better at portrait drawings. ive been practicing by drawing plaster casts from reference and drawing faces from reference, but any time  i draw them from imagination it looks weird, and I don't know what the fix is. the first one is just a bunch of one-line face drawings from imagination, and the second one is an oc of mine, also from imagination.


https://ibb.co/wYTkLBZ
https://ibb.co/cQPDqtP

I guess the question is: What do you find weird about them to begin with? Especially if your portrait drawings made with reference don't give you that feeling, what's the difference between them? 

Like to me your portrait doesn't look weird  - which isn't to say there isn't any place for improvement or advice to give, but it's solid enough where there isn't really an easy-to-explain fix that'll help you elevate your work. (Esp since weird is such an abstract concept to want help with.)

Drawing portraits from "imagination" basically means, that you are following a pattern of construction for a human face, often called an abstraction. Either one, that you completely came up with yourself, just from randomly associating your experiences of drawing with the experience of looking at a reference, or that you completely learned an abstraction someone else originally came up with by heart, and most likely than either of those, a mix of both.
You probably organize your attempt of drawing a face by some vaguely culturally known pattern you saw someone else do, or you interpreted an abstraction someone else came up with along the lines of your own experience.

If you feel like you are doing a lot of practice, but your experience doesn't seem to develop the way you want it to, I would suggest you try to train one of the popular abstrations for a bit, so you have a basis to decide how much of them you want to include into your own style.
Here are examples of the most popular I am aware of. With a bit of search engine fu you should be able to discover free tutorials for each of them on the webs: Andrew Loomis, Frank Reilly, Henry Bridgman, Steve Huston, John Asaro,
or even japanese industry style, which sacrifices natural proportions for style, and is mostly shared by a lot of japanese artists, look for Manga or Anime style.
https://line-of-action.com/forums/users/190807/replies?page=4
I am a bit lazy with the links. This link should lead to old posts from me, and if you scroll a bit down you should see examples of the results these different artists are going for. Generally Andrew Loomis is the first go-to, but you might already know him. If you already know Loomis heads, but feel, like they aren't doing it for you, you can check out those other artists. Becoming familiar with more than one of them also makes you more familiar with the entire concept of using abstractions for "drawing from imagination", which can help you you reflect on your own way of drawing faces and heads.

Generally, these are all artists, that come towards drawing faces from lines. There are obviously completely different approaches towards portrait painting, like approaching from value, but unless someone insists to read me write about that, i won't, because I barely know, that they exist.

Just jumping in to help, I think this is the direct link to the post Aunt Herbert was talking about above! :)

https://line-of-action.com/forums/topic/how-to-draw-heads-from-the-facial-expressions-practice?page=1#post-31765

thank you all! I'd say by "weird" I mean that they look childish, eyes look too big, and they all just look the same. I started out drawing anime and stuff and really only started actually studying 2 or so years ago. I tried the Loomis method for awhile, but found that it didn't work out for me too well, so I moved on to bridgman. I will continue trying and improving. thank you!!

Well, 'weird' is a very good and useful description for a problem many artists face. We start drawing something, and it feels all good while we do it, but when we look at the finished result, it feels like it doesn't meet our expectations.
So, if "weird" means, "did not meet expectations" what were those expectations to begin with? Are those really ours? Did we really have them clearly when we put out first line on the paper? Why and how did we fail them then?

The list of artists I have shown above has 2 commonalities for which they are famous: 1. They come with really easy to follow instructions (draw a circle of that size, draw a line in that direction... and 2. They produce results that match cultural expectations.

If you came from manga, then you already trained one such type of expectations. If you already looked into Loomis, then you already know a second set. These guys above offer yet more sets, focused on different aspects.

If you really feel, that the problem with your stuff is that it looks "weird", then the obvious answer is, learn copying one of these. If you really master reproducing one of this techniques, your portraits will be the opposite of weird. To the point, that they will be downright boring. If you want to make money by offering drawing as a service, boring isn't bad, it's reliable quality. But ofc it also stifles artistic growth.

So, if your aim is not to overcome your "weird", but to master it, and get to your own type of weird, don't treat any of these tutorials as gospel. These are toys, and you aren't done playing with them, until you can break them apart and reassemble them. Loomis measures the head differently than mangaka do, so does everyone of these people. And they are different to each other, but none of them is simply right.
You can end up with "same-face-symptom" after grinding Loomis heads the same way you can have "same-face-symptom" after dedicating yourself to manga. Bridgman has another perspective as well, but he doesn't overcome the problem, that while learning to draw exactly that way may overcome the problem of "weird", as you will be able to exactly produce the outcome you expected, if you just repeat it enough, you can't overcome "boring" that way.

Once you are familiar with a few of them, (and you know 2-3 by now) and so you know a few methods of measuring the head, you can try to compare how they approach the subject differently. You might not have the confidence to say "mangaka draw bad" (and it wouldn't be true), but you can now say, that mangaka eyes look different from Loomis eyes, bigger, and more childlike.
The next step would be to make the same comparison for the Inabatewil abstraction of the human head. If you don't think about any of those big cultural icons, and just start putting marks on paper, you are bound to follow some pattern, as human beings just aren't random.
You know manga, you know Loomis, you know Bridgman, observe Inabatewil, until you can compare what you naturally do, with what these others do, so you can make more informed decisions about what you want to do.

And then off course, you can compare any of those abstrations to references and will realize, that none of them really "naturalistically" fit "the reality". Because actual human faces are always weirder than the abstraction, unless the photographer and the make-up artist already put a ton of work in to normalize them.
Your drawings will stop feeling 'weird', once you settled the decision of how you expect the outcome of your drawing process to look. And weird outcomes are just the sign, that you are clearly not settled yet, clearly still experimenting, and there is only so much you can learn from other in this phase.
Best advice, stay weird, until someone starts throwing money at you for reproducing the style you developed for yourself.