I feel a little bit like you OP
Have 2 dcs, 6 and 3, DC1, the 6 YO was from a prev disastrous marriage and DC2, the 3 YO is with my now-DH
the pregnancy with my 6 YO was awful for many reasons, and he was unplanned. I split up with his dad when he was a few months old and met DH when DC1 was 18 months old.
the 3 YO was kind of planned, we were madly in love and the pregnancy was blissful, it was lovely having a baby with someone I really loved and who loved me back. The birth was amazing, she was a lovely baby and is a lovely little girl. And we both adore her. I really want DC3 and would love to go through another pregnancy and birth with my husband who i still adore like mad. But he is not as keen as me :( I think men think more about the practical aspect of it all, ie, money, space in the house, time factors etc whereas women often are more led by their hearts.
Anyway, I don't know if this will help but I just wanted to let you know that I understand the all - consuming urge for another DC. Its not clear in your OP - but are your other DCS with your DH?