Hey, not only am I pregnant and nursing, I'm pregnant and tandem nursing. So a few things:
Your supply doesn't get affected by nursing until around 12-24 weeks for most women--this early in pregnancy, it's probably just that you need to up your water or something you ate or just a regular fluctuation. Once supply dips (IF it dips, it doesn't always!), there's basically nothing you can do, except drink your water and nurse. Progesterone rules in the family of hormones.
This is more helpful for later, but identifying which nursing sessions are most painful and cutting back on them then (or in whatever situation it is) is a great way to save the nursing relationship.
Distraction--for you--can be another way to save the nursing relationship. If the LO is old enough, you can also consider night weaning, but while I did that with my first, it was tearless--two nights and she stopped asking (I just told her the 'nummas' went to sleep and made saying good-night to them part of our routine). My second is totally resistant, so she's not ready and I won't force it, she's only two.
So yeah, while I'm pregnant and tandem nursing, I don't plan to tandem nurse the whole way through. Five was always our plan for a cut off and my oldest's fifth birthday is before my EDD. Heck, I don't know if this pregnancy is even going to stick yet (I'm PALx2) so this may be my only post here, but I did want it to be encouraging. I ended up with next to no supply for months (drops if that) and it was like a roller coaster. I just nursed mostly on request, said no when it hurt and explained that sometimes I was sore and couldn't and--and this is important--made certain she never associated the baby with being told 'no.' I didn't want any resentment in that.
I talked about how the baby would bring new yummy milk and focused on the positive, re: nursing. I made it sound fun to share with the baby, etc. It must have worked, as we had no sibling rivalry until the 'terrible twos' met the "OMG, give me back the 'terrible' twos" three/four. They both hit the mine phase at the same time, but it never affected our nursing relationships, even if my youngest is super possessive.
So it can be done, even through hardships and yes, it was worth it. I'm very glad I stuck it out, especially when I had a baby with a weak suck and lazy latch who wanted instant gratification. I don't respond to a pump, but my toddler would nurse for a few seconds, stimulate letdown (and soften the engorgement) and then right to the baby, who would nurse. With all the other problems I had with nursing my second, having her sister there was a learning process, but it was also a great boon.
Most pain/aversion goes away with birth, but not always. For me, I had it toward my newborn's horrible latch until it improved. The pain didn't come back until recently, as my oldest is forgetting how to nurse as she is reaching the last stage of natural weaning.
Congratulations to everyone! I'm going to go lurk and worry over every little thing now, lol. Have amazing pregnancies and hopefully, I'll get to stick around and get to know everyone.