Mini rant about my boyfriend, advice ?!

I’m about 4 months pregnant & have been with my boyfriend for 4 years. We always knew we wanted a baby & etc etc.

the baby was not planned exactly but the baby was not “not wanted” if that makes sense.

Anyways when we found out we went through some mixed emotions of like can we do this, we’re still young, this wasn’t expected etc etc.

But he always said he’s happy and everything, he loves this baby, loves me etc. we told our families & his family’s reaction was so much better then he expected so everyone was happy on both sides. Anyways sometimes it seems like he isn’t so into this pregnancy, I mean he buys me food & everything, rubs my back if I ask him to but like when it comes to showing him baby clothes or trying to get him to sit and do the baby registry or look at different gender reveal ideas.. he isn’t so like involved. It upsets me and we fought about it before when I kept changing my mind about wanting a gender reveal party or not, it upset him that I kept switching it but it’s like, if we’re not going to talk about it together or anything of course I’m going to think about what I want on my own then.. he said towards that ^ that it wasn’t fair or anything & I couldn’t keep “changing my mind”

anyways we came to the agreement of finding out on our own before our families, us knowing the gender first through a cake from a bakery or something.. and even now he isn’t so involved into it, he doesn’t seem so interested.

Idk what to do or feel, it makes me sad that he isn’t as involved as he could be and when I bring it up, it like ends up In a fight between us.