You know, I was afraid to rock the boat in my marriage by bringing up the issue of kids when I was in our forties after I thought I was at peace with my decision to be childless by choice, so I really identify with what you say about waiting. By the time I melted down over my regret, it was too late for anything but DE. The good news was that 1) I was so thrilled there was a way to be a mom other than adoption (which was my first choice, but so difficult these days, especially for older women) that I really didn't care and 2) I never had to face that awful decision of when to move from OE to DE and 3) my family's genetics were a huge part of my reluctance to have kids when I was younger, so there was a large dose of relief in that forfeiture.
But you've had to face that awful decision, and I feel so much for you, but when you hold your DE baby in your arms, you're going to forget that DNA even exists. Yes, there are times when I see how little my kids resemble me and it aches a little, but my kids might not look like me anyway.
I know it must hurt that your DH isn't very emotionally involved. My husband and I were estranged when I was ttc, but there was an upside in that I had full control over all the decisions I was making. You may not have that kind of latitude, but in ttc, a little autonomy can be a real sanity-saver.
Wishing you success!
Maggie (in VA)