Need advice

Been  ttc over three weeks my period isn't du until May 7 but today after going to the bathroom I noticed very light pink blood not a whole lot nothing like my periods have been. I have endometriosis and ic so I'm trying not to get my hopes up so high dr said if I wasn't pregnant in 6 months we can start <a href="">fertility treatment</a>. The app told me not to test yet because it could be to early but how do I know if I'm spotting no sore nipples not yet anyway. Please help