Oh I am so sorry for your loss! I cannot imagine the pain and suffering of losing a child that late in pregnancy. You poor thing!
There is a such a thing as hormonal imbalance after pregnancy, and I don't know how common it is, but I have it right now (and I've never had it before) and a friend of mine has it too. I am currently breastfeeding, but my cycle always returns three months after the baby is born, and this is my 6th child. Not here yet and it's driving me crazy.
Progesterone counteracts and balances the estrogen. The estrogen builds up in your body until your period, and since you haven't had a period for 9 months and aren't breastfeeding, it's not healthy for you to keep that much estrogen buildup inside you. It causes long term health problems.
I think getting on birth control can regulate it too, which you might want to consider. There is a certain treatment that can make your period start, but I am unsure of the name. You'll have to talk to your doctor. Again, I don't know much about it personally, but my friend has this done as well. You can also try a progesterone cream to try to spike your fertility. It's called Happy PMS and is safe to use when you use as directed and safe for pregnancy too, and will help with your mood.
I hope you are successful: baby dust to you my dear.