Need Advice ASAP

Im currently 8 months pregnant with a girl. I have 6 yr old. My bf of 2 years has a 9 year old girl and a 5 yr old son. We moved in together about 4 months upon dating. My daughter's biological father was killed in a car accident by a drunk driver when she was 5 months old. So, my bf and family are the only father figures in her life. My bf and I are trying to take our relationship to the next level (marriage) but sometimes I feel that he singles my daughter out. He takes his kids out alot and never even invite my daughter to come. Before I was pregnant we all use to go out but it would be me & her & them. As if we all didn't come together. I'm so worried that when the baby comes she will be totally left out, all girls want "daddy" attention. We've talked about it and he swears he don't feel the way I explains it. I am willing to completely walk away from the relationship because I don't my daughter to feel bad or this to affect her later in life. Idk what to do. 😕