Not really sure if this is the right place.. looking for advice

Okay so first time ever posting here so please be gentle..

I (32F) have been with my partner (22M) for nearly 2 years now. Yes it’s a big age gap but we met at work and hit it off, there’s 10 years between his parents (dad is 10 years older than mum) and my mum is 16 years older than my stepdad and both relationships are 20+ years strong each.

When we first got together, naturally we were forced to have a lot of ‘serious’ chats early on, such as life goals, aspirations, and timelines for children and marriage.

We both said we definitely wanted kids, and he made it clear that he always envisioned having them mid 20s so it was something we saw as possible, given I’d be mid/late 30s.

Here’s the thing, we have just bought a house and moved in together (end of April) so we’ve been bickering a bit more than usual, and a couple of times he’s thrown it at me that he wouldn’t want to get married or have children with the relationship the way it is. I agree but feel like it’s an odd thing to say over an argument about chores etc.

I’ve challenged it and asked if there’s more to it, as it’s come up a few times now. He’s now saying “in an ideal world” he wouldn’t be looking to have children until he’s at least 30, that he feels like he would be “trapped” and miss out on “learning, growing, making relationships, and travelling”. This is something he’s never mentioned before and it’s really floored me.

It’s turned into a much bigger conversation about him worrying he’s going to decide he’s not ready at 27/28 and feeling guilty for taking the opportunity away from me - my issue with this is it sounds like he’s planning on leaving me at that time to pursue a life with someone who can give him kids later on.

I completely understand he’s valid in how he’s feeling, but am I overreacting to think he’s planned out his future without me in it, but it feels like he just wants to stay with me now, knowing if he changes his mind later he’ll be okay either way. The phrase “you have a timer but I don’t” has been used..

Not sure what I’m looking for here other than some reassurance that I’m not going crazy and I’m right to feel anxious about this, and maybe some tips on how to approach the conversation again? It was left with him rolling his eyes at me being dramatic so I haven’t raised it since.