i can totally understand the dilemma you are faced with as i am in a similar situation, i am currently TTC my first child whilst taking lithium. I am having problems conceiving so cant come off my meds as i dont know how long it will take and along with the 9 months of pregnancy, i dont want to be unmedicated that long.
I have 100% decided that i will stop taking my meds if and when i discover i am pregnant, as through my own research i have discovered that manic symptoms are generally more controlled during pregnancy, and that depressive symptoms are more likely to be the problem, particularly after the birth. For this reason i have also decided to go straight back onto my meds immediately after delivery. it will mean i cant breast feed but i dont really have much choice.
My decisions have took a lot of time and thought and i did consider not having children at one point but it is my dream, so i have decided with the help and support of family and friends i will battle unmedicated through the pregnancy if and when it happens.
I am also lucky in the fact that im bipolar II and my symptoms have mostly been mild, so your individual situation needs to be taken into account too. Talk with your doctor and make sure you have all the information and advice necessary. I dont believe theres a right or wrong decision in this situation, but just make sure its an informed one