My best friend has BPD and is an amazing mom. She has three daughters and has been off and on meds for years throughout her pregnancies and through parenting.
I don't know how things will be for you but I hope you and the baby feel safe and at ease together. As scary or tough as it may be, my only advice is to be very honest about how you are feeling. Even if you are afraid of what your honesty may mean.
I have big polar this is my third baby and I have never had a problem in facti wouldn't let them takemu daughter to the nirsury period. This baby is going to have to spend a brief time in nicu and that is whatmakes me the most nervous