IUI confused 🤷‍♀️ help?

So I had a trigger shot on 7/15 and IUI was 7/17 so I am 16 days post trigger and 14 dpiui. With previous IUI's I've started AF at exactly 14 days post trigger shot. Once at 13 post trigger and once at 15 post trigger(each was preceded by spotting) Now this time, I was prescribed Prometrium and have been reading this can potentially delaying AF, but I have zero AF symptoms. No spotting, no pimples, nothing like normal. So I don't know if the Prometrium is delaying AF or if I may potentially get a late bfp. I've had some cramping/pressure, fatigue and backache, but have also read that the prometrium/progesterone can mimic pregnancy symptoms. My doctor said to test 8/3 if no period but since I've gotten a BFN today I have no clue what's going to happen. Has anyone gotten a late bfp on a medicated IUI cycle or have any insight??