This was very common for me after a stimmed cycle. I also have PCOS and always thought it had something to do with that. I would always get my hopes up that it was implantation bleeding and it never was. Just my body acting up.
Having said that though I did also have implantation spotting with this pregnancy at 7 & 8 days past my 5 day transfer (so at 12 & 13 days past ovulation or in my case Egg Retrieval, but you get the idea). Mine was not clots though, but rather brown with some red and pink moments. I also cramped ALOT!! More so than I ever do with AF normally.
Unfortunately all you can do is do an HPT and/or wait it out to see what happens. It isn’t uncommon though to ovulate on a natural cycle just following a stimmed one though so anything is possible. If you get to where you believe you would be about 18 days past your ovulation and you are still getting negative HPT’s then your odds of being pregnant at that point are less than 1% if that helps you gauge how long to wait to see.
Hopefully either you will get a positive or AF soon so you will have an answer one way or the other. It is tough being in a place where you aren’t sure what is going on. :grouphug:
Good Luck! :flower: