You will know if she isn't getting anything is she cries and acts hungry after you have fed her , the first milk "colostrum" is very important for the baby right now and your milk comes right in afterwards.
Your full milk supply doesn't come in for 3-5 days after delivery. She's probably just getting colostrum right now, which, is ok thats what she needs. If she still seems super hungry after you finished than you can always supplement formula til you supply comes in.