12DPO questions

All weekend I’ve been super bloated. Nauseous. And really bad indigestion. I have IBS and endometriosis so the indigestion and bloated are normal, but this was more severe. My Lower back also hurt. Today I had very light pink when I wiped. Though AF was showing her face early. Put a tampon in and went about the day. Went to change the tampon and there was very very little brown on there.

If this is “implantation bleeding” when should I test? I tested yesterday at 11DPO and BFN

Side note: I have PCOS, stage 3 endometriosis and hypothyroid. I have a less than 3% chance of conceiving naturally. We start IVF next month. No clue why I’m even giving it a though that this may be the BFP I’ve dreamed of for the past year 🙄🤦🏼‍♀️