Hey there Dani, good start so far :)
I definitely recommend not only drawing from photos though. If all you do is draw from photos then after a while you will be able to draw from photos REALLY well, but when you do anything from imagination it'll look like total garbage. Now, it's good to keep studying, you gotta train your eye to see all sorts of things, but I think what's most important for you now at this stage is to learn what those things are that you have to train your eye to see and study those specifically.
For all of those studies of nude women you've done you could be studying many different things from those, values, colors, skin tones, anatomy, gesture, form. But at the moment you're just copying the image, trying to get it to look exactly like the picture and not learning too much along the way other than how to copy pictures better. I really recommend taking the time to study things one at a time, for now you should be looking at anatomy and gestures and probably do some periodic life drawings as well. But only paint in black and white for now, once you've mastered values then you can move on.
Look at Loomis' books or Hampton's anatomy book and study from those and go to http://www.quickposes.com/pages/timed
to study gestures. Study the shit out of this stuff if you really want to improve, study it and THEN draw from imagination, try and train your memory to remember poses, muscles, etc. etc. Drawing from imagination is really important if you do want to improve so don't forget to make time for it, your drawings from imagination might not seem all that great but you have to do it anyway ha.
Obviously, still have fun with this. Don't lose sight of why you enjoy drawing or want to get better at it. If you really really REALLY don't feel like studying anatomy or something then don't stress it, paint or draw something that you do want to paint or draw. Just remember to study smarter and not harder and you will save waaaaay more time, trust me :)
Hope I could help, and please stick with it <3