Vegetarians & Vegans Support Group
Vegetarianism is the practice of not consuming the flesh of any animal . Veganism excludes all animal products from diet and in some definitions from attire also. Vegetarians have varied motivations including religious, cultural, ethical, aesthetic, environmental, social, economic, health, political, and personal concerns. Join many others in sharing your experiences to...

Could you and your boyfriend go to a doctor you both agree on together and sort this out with her or him?
I don't know enough about this to give any advice one way or the other.
If worse came to worse, you could go off your vegan diet just slightly during pregnancy. I think Natalie Portman did something like this and after the baby was born she went back to full vegan.