Please help! Ovulating, getting bfp, then having chemical pregnancy!!

After I got off the shot I THOUGHT the reason women couldn’t get pregnant was because they didn’t ovulate and that it took months for ovulation to resume.

Well I’ve been off for 4.5 months and I have gotten 4, yes FOUR, bfp!! Every single one ended in a chemical pregnancy. Not only that, but only 1 of those actually consisted of me bleeding(first one).With the other ones I did not bleed so I only knew I had one because of my tests. This means that every damn month I can get “pregnant” but I don’t want to spend any more money on tests and be heart broken every single month. But how in the world will I know if one of these times it finally sticks??

My real question is, why am I getting pregnant and loosing them? Has the shot thinned my uterus? Does this mean that I can’t hold a pregnancy for 9months-2 years because of the shot? I am so freaking heartbroken, I refuses to interact with my nephew who is 1.5 years old at Christmas because I didn’t want to cry. I feel like I’m dead inside.