Ladies with Endometriosis-HELP!

Alright so I never keep track of my period and I frequently turn to this app to give me a clue on where I'm at. I looked to see that I have completely missed my period (was supposed to end 3 days ago, but it never even came). While I WANT to immediately assume that I am pregnant, I have to keep in mind that I have endometriosis and this may be common. So, what do y'all think? Last month I was hoping I was pregnant due to breast tenderness, then got my period a week later.