Late period & lots of eggwhite discharge?

My period is three days later than the app predicted, but while my cycles are normally slightly irregular, they generally follow a pattern of 27-29 day cycle, 30-33 day cycle, repeat. (Most often, 28-32-28-32-etc)
I already had a lot of discharge two weeks aho, combined with heightened maternal urges (two things I thought were my ovulation signs), this month is a 36 day cycle now...
I'm having none of my normal period signs. No lower back cramping (I always have that in the two days beforehand), no appetite or acne increases, nada.
Four months ago, I had unprotected sex. It may have been the day i ovulated. My period was a day later than I expected and I had thought I had pregnancy symptoms, but tests 16 days after sex showed up negative. 
That period and the two since were all waaay lighter and less painful than mine normally are. 
Could they have been breakthrough bleeding, rather than periods? Could I be having a cryptic pregnancy?
I took a hpt two days ago, it was negative, but it was a dollar store one... Am I just being paranoid?
What other reasons for a lot of eggwhite discharge could there be, when it's time for a period and, if i'm not pregnant, I've already ovulated?