Am I overreacting for no reason?

I’m 22 and am in my first relationship. My bf has been in 2 other relationships before ours (first one when he was 16 or 17 - around 4 or 5 years ago). Part of me wants to make it official and post pictures with him online, change my relationship status, celebrate 3 months together, 7 months, etc. — but he’s not really into any of that. He’s already done it. He’s always hated social media and I knew that going into this. But I’ve always wanted a relationship where someone will post about me once in a blue moon, or at least acknowledge the little things.

It sounds stupid to say but maybe I care too much about social media or milestones and I shouldn’t? Is it wrong of me to want to celebrate little anniversaries and milestones or post a cute photo with him on a trip to Chicago, etc.? I get that he’s done all that and that’s why he doesn’t view “2 months together” in the same way I do. But to me it’s special because I’ve never had any of this before and I would love to celebrate it. This morning he laughed because I said “happy 2 month anniversary” and he said “are we gonna act like high schoolers and post about every little month because you never had any of that?” I know he was joking from the tone in his voice, but it hurt my feelings. Yeah, I would like for us to at least go out and grab a cup of coffee... it’s a new experience for me and I’d love to celebrate it. But maybe I need to grow up and just celebrate big things like a year together? Idk... I’ve always felt like I missed out on that HS romance and it’s too late for me to acknowledge the milestones in a relationship. I may be overreacting but a small part of me can’t help but feel a little bummed...? Is it dumb to feel sad?