I agree your priority right now is to stabalize first. A pregnancy causes a lot of emotional shifting due to hormones to begin with. You want to be in the best possible state of mind. I say this but I was in trauma during my last pregnancy, but it was mostly depression and not hypomania, but I still know I didn't take care of myself as well as I should have. I am greatful today that my son is very healthy and he made it through my emotional turmoil. (But that pregnancy was 100% unplanned.)
Also once the baby is born you have to be in the best condition possible to care for him/her. New babies are a ton of work and with both of my son's I had post-pardum depression as well as my normal "craziness." With my first son I somehow made it all on my own but with my second I had help from my husband and his family. Even still that was the most difficult stage of my life for more reasons than just the baby.
Also, being unstable in your relationship puts a strain on you and your boyfriend. Having a baby together will also add to that strain. Although you are making a family when you have a baby, it does put a great deal of stress on everyone. So you want to make sure your relationship is in the healthiest place possible, too. Once you have all your ducks in a row, then talk to your doctor as previously suggested.
I hope for the best for you and just remember that by waiting you will be the best mommy you can be for your baby.
I would be careful right now as the most important thing is to stabilize. Best to go back on medication and then make the decision as regards having a child after that and then plan out with your psychiatrist and OB-GYN as to what medication you could take. And of course your psychiatrist would know the specifics but if you've been off Lamictal a while you'd have to go back on it at the same rate you did before so while that's being done perhaps they could give you another medication in the meantime just to stabilize things until the Lamictal kicks in. Its a decision that has to be made when everything is adjusted and stable as there is a lot of planning and general issues with life involved and its a full time committment.