Am I seeing things?!

Am I only seeing something because I want to so bad? Ok back story, I have been to a fertility doctor and they did all of the necessary tests on me and my husband. Everything came back perfect except my progesterone. I tested negative twice last month. My last period was April 22. On Monday I started spotting dark brown/light pink. I have been spotting off and on since then but never enough for tampon. Is it possible to have implantation way after a missed period? I have been testing and all have been negative but I swear I see something here.