NB you won't be able to continue the relationship..unless you marry. Have you been together very long? It sounds to me as if the mania caused you to get baptised!!!
Btw you mention you're unmedicated. Does that mean you're not diagnosed properly? I only ask because sometimes younger people can be mistaken for bipolar when they're actually ADHD.... particularly girls. Females with ADHD can present quite differently.
I've never heard of anyone's baptism being annulled but if you can prove you were unwell when you got baptised it's possible....we need the ex elders on the board to weigh in on this one. Apparently rules have become more relaxed recently.