"nicer than you deserve" - you're as deserving as the next person, CC. Stop knocking yourself - I know it's easier said than done, but I do think you need to get some help. Your wish to have a child is becoming something of an obsession and colouring all the rest of your life at the moment, which isn't keeping it in perspective. We don't all get to have children, and although you might not want to consider that possibility at the moment, there is plenty of life without....
On the practical side, what happens if your husband just doesn't get that promotion, and you can't give up work for a couple of years? what will you do with your hard-earned degree if you don't find a good job once you graduate? - there is so much else to take into consideration.
IMO some counselling would help, especially as you feel a bit better from having written it down and telling us about it.