I feel your pain, mama. We're bfing. My ds is 18mo. He bfs about every 2 hours. This is my second pg while bfing ds and it gets better and worse and better and...
I can definitely say, it will be less painful once your lo is born. How's that?
For my last pg (which ended last fall), my nipples were incredibly painful the entire time, but I stuck it out and kept bfing. There is nothing better than a nursing toddler to help once your milk comes back in. I never got engorged and it was fun just to see my little guy doing the happy breast dance when he realized "milkies" was back.
I found "Adventures in Tandem Nursing" and "Mothering you Nursing Toddler" to be really helpful reads. Have you read these? There are lots of strategies for handling the soreness, heebie jeebies, etc, that can come up. If you've made it to 19mos, you're probably already reading in the bfing beyond infancy board, right? Those mamas who've btdt really helped me when I was in so much pain and weighing the options about weaning. I really just needed the support to get me through it. I'm not trying to urge one way or the other, but just to let you know, just about every pg, bfing mom has these issues come up. It was nice to know that if I weaned while pg, it wasn't necessarily weaning forever, too. And that there are different degrees of weaning, which it sounds like you might be utilizing? Kinda takes the pressure off when it hurts, having it not be all or nothing.
This pg, knock on wood, I haven't had sensitive nipples and my milk supply hasn't dipped. But, if I do have these, I'm still determined to keep going.
For ds and me, I feel like bfing while pg is another challenge along our bfing journey and it will be so worth it when we move onto the next one. It's such a short time we get to share this special bond.
hth. Good luck to you