Megan, since Tracy is nursing alot more now and eating less solids, you say, that will increase the prolactin in your system. Prolactin has the ability to suppress/delay AF. Most likely, Tracy's change in nursing has delayed AF for you. Cycles are notoriously not regular for breastfeeding mothers. Just how it goes. As DaryLLL said here once, 'welcome to the wonderful world of breastfeeding!'
For less than the cost of an OTC HPT, you can get Chaste Berry tincture (aka Vitex). Taking that everyday will regulate your cycles naturally, despite the elevation in prolactin. Chaste Berry is a natural progesterone.
We all have only like 25% chance of conception even in the best of cycles. Add birth control (condoms) to that picture and your chances of conception are incredibly low, as any doctor will tell you.
Sorry this is such a hard time for you. I really recommend the Vitex as your cycles have been very irregular. It is also a fertility enhancer for women who have infertility/miscarriage in their history.
All your symptoms are indicative of elevated progesterone as AF approaches. Plus any additional emotional stress you have over this difficult time!
Good luck to you and enjoy your baby!! Sounds like he is doing great.
P.S. How did the visit to the pregnancy clinic go? Like I said, I've found the clinic volunteers SO wonderful. And the tests are guaranteed to be not-a-dud!