Nice work! Especially that vampire on #4. I agree with the above comment, you work better with refs, but that doesn't mean to stop those from imagination. You should just aproach using refs a little differently. Use them as studies: pick a focus, say value, and work on capturing all the values in the ref on your canvas. Try to the understand why certain values are the way they are. Work on understanding rather than just copying.
Anyways, there's my 2 cents. You've got the right stuff. Keep going!!
"[...]as we gain facility of hand and travel further afield, we discover that we have a key to unlock the wonders of art and nature, a method of conjuring up forms at will: a sensitive language capable of recording and revealing impressions and beauties of form and structure hidden from the careless eye[...]"
-Walter Crane, 'Line & Form'
The studies are a good start. Make sure to take your time there and think about what you're doing there. No mindless painting while studying or it'S going to be some wasted time. But there are some nice parts already =) If you can transfer a bit from it in your own paintings you're on a good path.
In some of your head drawings I notice that you tend to make the back of the head very small. Have an eye on that! Take a look at real human heads and start measuring the proportions and see there you might went wrong. It's a long journey to get human faces and heads right because anyone will notice right away that something is off. But patience and a lot of practice will help. Keep going =)