these are my thoughts...from my experiences...
when i was 19 i got pregnant with my long-time boyfriend and we later got married...it was unplanned and i have NEVER regretted that...although him and i are no longer married i have NEVER regretted having my baby or being with him .....a little while farther in life, i met a man that i later married (still married to)...after we had been together for maybe 3(?) years we went ahead and had a baby...i didnt particularly want to have more children BUT i made a CHOICE to give him a child which was something he passionately wanted in his life...and let me be clear, i CHOSE to do that for him and i have NEVER regretted that choice either....i love both my children with all my heart (probably more than either man i've married lol) and i have NEVER looked back and felt regret over any of those decisions
however i do NOT plan on having more children...both pregnancies took a toll on my physical and emotional health..lots of weight gain with both...the childbirth for both children was long, difficult and traumatic...that being said, i am 34 now and plan to focus on MY health, MY body and do not want any more children...ever...my DH knows that and, at this point, he is okay with that although i think he would like more
if DH gets to the point where he desperately wants to have more children, then that could become a dealbreaker for us...as he deserves to have more children if he wants, and i also deserve to NOT have more

Glad your BF seems to understand now.