Reminds me of my attempts at painting rather than sketching! I recommend first off that you use reference if you are not already.
I suggest you simplify, the shapes and likeness is there! But it feels muddied at times, I think because you are trying too many shapes and colors at the same time. Try a 2-tone or 3-tone piece. For 3 tone, that would be base, light, and shadow. Look at comics & manga for inspiration. They get away with a lot by doing very little.
By simplifying into fewer colors, you force yourself to "edit" the picture more; to digest it and then re-render it your own way. Always look out for shapes that can be unified together into a larger one.
Most fantastic efforts you've put into your memorized figure, fnibbit. However, when in doubt, please refresh yourself by studying and memorizing with the reference actually in front of you. The reason why you could and should do this suggestion is because, it's a lot harder to draw anything from memory if your memory is not your sharpest. But don't give up, if you learn so much from your model, then your memories will become their sharpest with most practice as you could get.
For more details, look at this vid below.
Hope this advice is extremely helpful and beneficial.