I want to know my bf's family's mental health history before we start having kids
That's an odd request. Why do you think that that is important?
Because I want to know if the kids will suffer from mental illness
I get that you want what is best for your kids, but you cannot assume that they will inherit any mental illnesses from family members. I think that it is good to know, but that should not make up your mind about having children and with whom.
I think you should leave my boyfriend out of this, it is my decision. I already notified him we should wait at least 2 years before having kids.
It's wonderful you are thinking for the future and planning accordingly. A child should not suffer, as it is not brought into this world by their own choice. Sometimes it's better to not have one if there is a history, and you are making the right choice