For simplicity we will say you're modeling an anime female. Anime females are slim and rounded off with little sharp edges. I feel you approached it a bit too realistic which is why it looks off from the reference. Things like your head shape, neck width facing user, nose, and eyes immediately pop out at me because of this. I would say model it as you see it and do not be afraid to push and pull your mesh. For example, if you look at your reference (legs specifically) they are rather thick and they don't taper too much versus your base mesh that does. I hope I wasn't too harsh with this critique. If I was, I apologize. I figure if I give you every last possible issue I see you'll have a good starting point to edit etc. Good job so far though, and I'm looking forward to seeing how it turns out!=D
