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.)