Hey there! Just dropping by to give ya some tips on this anatomy practice! ^^ Well, here we go!
One of the biggest things I noticed were the shoulders. In this drawing they don't have much shoulder at all. To get a feel, I seriously recommend looking at yourself in a mirror or finding a good model in either a friend or online. Mirrors are wonderful to see if poses feel natural or for realistic anatomy. Try it right now! Look at yourself and first focus on those shoulders. Each person is different, but looking at myself, my shoulders are broad enough to fit about 2 and a half of my heads side by side. That's how wide they are. How many for you? Also notice the way they slope downwards into your arms. Return to your drawing and you'll find your character's shoulders are only broad enough for just one head.
Also look down at yourself right now. Hold your arms out like they are in the drawing. It's good to judge how long to make the arms. How far do yours extend. Personally, mind extend a few inches below the crotch, while your character's is a bit above. If she put her arms down, they'd be a bit stubby.
The rest of the body is a bit wonky, too. It kind of feels like you aren't entirely confident and it shows in the work. Strange proportions, really thick indecisive lines... To relieve that, I'm going to drop by some things on you. Look at these tutorials. Tutorials REALLY help. Use both them and the mirror trick all the time. Try the pose yourself to see if it feels natural before you draw it. Then draw line for line all the tutorial drawings. Copying is fine in private used for practice. Do it until you get a good feel for things. When you combine elements from all kinds of tutorials, then you can try to make up poses on your own and post them online as full, confident and lovely drawings. ^^ You'll soon find your own style that will feel more realistic and natural. But never stop there, remember, continue to grow! ^^
Here are some tutorials. Remember not to rely on just one tutorial- even they have flaws in anatomy. Some are cartoony, some anime, some real. I don't agree with all of them. Try all kinds and always strive for more realism and natural looking people! [link] [link] [link] [link] [link] [link] And those are just a few! Keep looking for more as long as you need them. ^^
Here is a lovely group for all kinds of poses that'll be hard for you to do on your own: [link] All kinds of lovely models to help keep it realistic.
Oh, and for future drawings, there are all kinds of tutorials out there for drawing lovely hair, faces, etc. Throwing a few your way- [link] [link] [link]
Oh- and really remember that breasts are like water balloons. They are influenced by gravity. That is a rather common problem a lot of people face with female characters: making gravity-defying perfect sphere D-cup boobs when they're more like tear drops and droop! If you need help they have tutorials for that specifically, too. Plus references and yourself.
Anyway, I hope this helped you! Good luck with your drawings. You'll be lovely in no time!