My first, my fiance's fourth. He's been there done that and now I feel like I'm going thru this alon

I am pregnant with my first child. The only thing is my fianc? has three girls from a previous relationship with an ex girlfriend. This one will make four. They all live with us. However, being that this is my first, I feel as little alone because he's done this already and has experienced this three times. The things that are exciting to me like her moving and all doesn't seem to phase him. Sometimes I wish his daughters lived with their mom because its taking away from my baby's moments. I won't get to decorate a nursery...or have that bonding time with him and her. How do I overcome this feeling? I don't want to treat them any different, nor do I want to make them feel left out, but I want to make sure my baby will get all the same opportunities as his other three did with him. Advice....please...help!!