Is It Normal To Have Brown Spotting On Day 37 Of Periods?

I had a hysterscopy 2 months ago for stage 3 endo and a bunch of polyps on my uterus (btw- trying to get pregnant). I had a normal period a month later- 6 days, bright red, and normal. I always do the gross brown spotting for days before and in between my periods (also have PCOS). 2 months later, now I am on day 37 and started spotting dark brown as of yesterday again! Going for ultrasound tomorrow to bring on my period, so we can start with artificial insem but does this sound normal? It's driving me nuts!