Question: pregnancy/ past abortion(s)

My Fiance' and I have been trying for a baby for over six months now. I have two children from a past relationship, after my second son was born I got pregnant again and decided to end the pregnancy. This was almost four years ago. I have had almost every single ultrasound, blood work up, and fertility test imaginable done to me recently. It has been a very long, and hard road especially when I see all these people around me getting pregnant and having kids. My Fiance' has no kids of his own. I have one test left the Drs wants me to complete. Where they check to see if your tubes are blocked or not. My Dr doesn't think they are, but is doing this to rule it out. I havent been on any birth control for over a year. My periods were pretty regular, but while waiting to do this next test (I have to wait for my next period) I skipped my period. It is officially now, two months late. I am not pregnant, and I found out bc they did two blood tests.