Pregnant but want to be single...

I've always been that person who just doesnt like being in an official relationship at all. I just enjoy being exclusive to one person but dont want to start calling them my boyfriend or whatever. Anyways we have a baby on the way and he expressed how much he wants us to be a complete family and wants to even marry me in the future. Everything sounds so sweet and nice but I dont want to be in a relationship. I enjoy what we have without the labels. Just 2 humans being exclusive to one another. It stresses me out almost ever day because I feel like I should just give in and just do it because it's the normal thing to do or that maybe I just got a few screws loose and ruining something that would be beautiful. I just feel uncomfortable thinking about being in a relationship, let alone getting the government involved and calling it marriage. I just need to hear someone elses opinions and thoughts on this. (extra info: I'm 21yrs old and live on my own away from family independently.)

Update: guys, it's not like I dont claim him. When people ask of course I tell them he is my boyfriend, I do claim him. It's not really about the labels. Idk I just feel uncomfortable being official because maybe I just feel like im settling or something. We are both excited about the baby and I've known him for 2yrs so he isnt a 'stranger' (I can only know so much about what people allow you to know about them). I just have a hard time putting trust in him because my woman intuition is telling me not to. So therefore, I really dont feel comfortable officially being with him and I dont feel comfortable calling him my boyfriend until I feel that I can risk my emotions for him. It's just something seems off about being together and I cant figure it out. I've always dislike the feeling of being in love so I guess I'm just trying to hard to stay away from it all.