So a serious question about the bane of our existence, periods.

So the last few cycles tht I've had (or at least when I've been noticing) is that I've been spotting halfway through my period. It starts as a light pink/light brown and the closer it gets to my period the darker it gets. It's never super super heavy but enough to wear a panty liner. Does this happen to anyone else? I'm definitely not pregnant. Took so many tests to rule that out. I was thinking maybe birth control. I'm making an appointment to see my doctor but wanted other voices too! Thank you gals ❤️