Mariah- here's my "diagnosis"
on day 2, was he popping off b/c he was falling asleep? common and normal, but if it happens again, just try to wake to nurse more often.
Your milk will pobably come in faster the 2nd time around, and the idea is to keep baby feeding so you don't get really engorged. You should feel full as your milk is coming in, as this is your body's way of figuring out the supply and demand thing. But if you nurse every 2-3 hours, baby should "relieve" enough milk that you are comfortable and so that your breast is not too hard to latch onto.
If you do get engorged again, you can express or pump right before feeding to soften up a bit, the latch baby on. MAybe even express a but in the shower before feeding baby. Don't pump too much, or your body will just make even more milk.... just pump to comfort so baby can grasp softer tissue.
When you latch, aim your nipple for the roof of baby's mouth instead of the throat. This will help baby to get a lot of lower breast tissue on his tongue/lower jaw. ALso, if baby is reluctant to stick his tongue "out" enough, you can work with his tongue by using your finger for him to suck on, and as he is sucking, apply downward pressure and slowly pull your finger out of his mouth... to encourage his tongue to resist against your finger and to extend.... I hope that makes sense!
Using nipple shields as a last resort is a good idea.. there is definitely a place for them as they can aid in getting over a rough time period. ANd breast milk thru a shield is still better than having to stop nursing all together, KWIM?
I think that if you pay attention to latch early and watch and avoid over-engorgment, that you will be okay!!!
HTH and good luck!!