Baby mommas

So I've been kind of going crazy lately about some things. I have been with my boyfriend for 7 months now and he has a 2 1/2 year old son with another woman. I think I've been doing good so far dealing with all that. But for the last 3 months we have been trying to one of our own ( hoping for a girl!) And I just can't shake this feeling that he may leave me since he already has a family with someone else. He doesn't act like he wants to leave me and is very loving but I just can't get it out of my head. They work together all day and even play softball outside of work on the company team together. I just feel like the babysitter. Idk. Anyone else have to deal with baby mommas?