Hi Lindsay and welcome to the forums. Many congratulatiions at the safe arrival of your son!
Lots of us have been in your shoes, committed to nursing and yet obligated to take the medications to protect our own health. Obviously, you need more help and support with regards to the best medication for you. I nursed my daughter after my experience of preeclampsia and HELLP with some Procardia on board. The only thing that bothered me was the horrible metallic aftertaste.... but I guess it kept me drinking my water!! There are a range of medications for treated elevated BP after preeclampsia, and I fear that you may have to push to find one that is effective and tolerable for both of you.
you can afford to be patient. If you son is responding so significantly to the labetalol in your breastmilk, then obviously you have to pass on nursing for a couple of days to flush it from your system... but that shouldn't be the deathknell to your breast feeding plans if you take the long view. Seek advice from a lactation consultant, there may be one associated ith your hospital, about what to do to manage interruptions. Don't despair, there are moms of preemies and neonates with medical issues who have had to deal with similar "pauses", and who have managed to develop longstanding nursing relationships. Lucy and I didn't meet until she was nearly a week old, and she didn't even get a chance to nurse until she was 10 days. She turned out to be my most accomplished (never raised even a blister, never bit) and longest (16 months and only because I reclaimed my boobs and personhood for a few months before delivering the next one) nurser.
You need to remember that you are still immediate post-partum at two weeks out. The risk of post-partum preeclampsia doesn't wane completely until at least 6 weeks, so you remain somewhat in the danger zone and your meds may be very necessary. If I were in your shoes I'd want to try everything before I opted to go off the meds. Prolonged elevated BPs aren't good for anyone. A balancing act is perhaps required. I'm thinking that your worst case senario is having to go back on the Procardia... baby will be happy, but could you handle the side effects?