Question....

Do you not want kids....ever?

If you don't, then do him a favor and end things now.

The kid issue is a major life decision and its important to find a partner who is on the same page as you.

If its a matter of not wanting kids now, tell him that you do not want kids now but you might in the future.

It sounds like he is being a bit possessive IMHO.

You're quite young, and I have a feeling that if you settle down with him now, you may regret all of the things you could have done in life....but didn't.

Hugs.