I would say that if you like the sharp lines, then keep them.
Trying to get softer or more flowing lines may not loosen up your images or get you what you are going for. I would say that trusting yourself will. And I think you need to trust yourself. Because you have a very good grasp on anatomy here and it shows.
Might I suggest you look into holding your drawing utensil underhanded rather than in the traditional writing grip.
If you look for "Artist Drawing Grip" you will find videos and articles explaining what I am talking about better.
I know what I am talking about and trying it out right now. I got Koh-I-Noor Clutch pencils (5.6mm thickness) therefore. I also played around with a whittled pencil, but it doesn't give me quite the confident feeling I'd like to have.
Thanks for the advice! I didn't put that much work into that so far. I will work on it!