What's wrong with working from refrences, now?
Honestly, unless your some kind of genius, it'll take a very, very, very long time to 'memorize' the human anatomy 100%. I'd advise against aiming for that, since it's a rather unrealistic expectation.
What you can do though--is develop a solid understanding of how the human body works, and use that understanding as a tool coupled with useful reference images for the few things you may not be 100% certain of--and take off with that.
I'd never advise writing off the use of refrences entirely. The human body is an odd, quirky entity--and it will do countless weird things your mind wouldn't be able to conceive on its' own without a little help from life or even reference photos.
Of course, obtaining and maintaining that solid understanding still requires you to draw the human figure from life over, and over, and over until the day you decide to quit art ;]
.Always believed we could fly
Through this life of bees.