This OP! I'm in the almost same situation as your are now, except for 6 years instead of 10. I'm turning 40 next week so my chances of having a child are moot at this point. I have to grieve this on my own as my partner regularly forgets this is something I wanted (and even led me on at some point) and how it impacts my mood. It's extremely difficult on top of the emotional turmoil I feel about the relationship right now and I feel like I can't even grieve openly to not make him feel bad about it.

You mentioned he is avoidant, if that helps, for your own closure, I recommend heading to freetoattach.com that cover avoidant's dynamics. The gist is, if he doesn't want to become aware of this and not work on himself, nothing will make him, no amount of nagging, pleading, etc. But do this to get a better grasp on things not as another attempt to change him or making him see things.

So, if children are in the picture for you, do something about it. Perhaps he will agree to children but in all likelihood, you'll be a single mum in a couple. You still have time to find a partner who will intentionally want these things with you (you can also check the blog Sliding or Deciding that covers unasymmatrical commitment in a relationship). Just don't let the years pass you by.

Sending lots of hugs and support.