Teething is a very possible reason, so is developmental changes. Lots of babies wake at night and stand up when they can... because they can. Is she good at sitting back down on her own? Maybe she is still having problems with that part of standing/sitting and when she stands at night, she doesn't think to sit back down. Beginning to crawl can also affect sleep habits. And, as you said, she could just be hungry due to a growth spurt.
My son was not a good sleeper (just started sleeping through the night at 16 months). Some of the things I tried included, nursing (which you are doing), sitting by his crib and "helping" him lay down and stay with him till he goes back to sleep. I introduced a "lovey" at around 5 months, and now he is totally attached to it, and I think it helps him at night when he wakes up. His is a little blue blanket bear, and helped with weaning too.
Good luck!
J.