Breastfeeding in the NICU

The day finally comes when the nurse let's you know "how do you feel like trying to feed today?". Try not jumping up and down while cheering (they don't like it).
You will get there. Remember if they can take a bottle then they can nurse, which is actually easier! (especially heart/lung babies, according to the American heart association and the American lung association). You specific NICUs policies will determine how willing/excited they are to let you nurse. Don't forget that "we want him to use a bottle so we know how much he is getting" is a mathematical reason, Not a health one. By the time I got to nurse I could tell them how many oz he was getting.
All of the pumping you have been doing leads up to this moment.
Many NICUs will offer you a lactation consultant... You will know how good they are fairly quickly. Just like in everything else term and preemies are a bit different. With term babies you use the "sandwich and stuff" method. You have to be a bit slower with preemies.
For preemies express a tiny bit (hey pumping queens know how to do this in their sleep!) and let baby try and taste it.
Try and relax at the first few feedings. It is not totally instinctual and it may take a few times for you both to figure it out. So allow yourselves that. Try not to let the nurses stress you out, some will some won't.
Nursing in the NICU (at least ours!) is a WHOLE other level of NIP (Nursing In Public). I had a huge window behind me and we were right next to the entrance so everyone passed by us. I learned to use my faux moby wrap and became very comfortable NIPing.
You will get there, just keep up hope.