Please explain.

On Dec. 25, 2018, I had light pink spotting. This continued till the 29th and it had turned a brown color. Eventually it went back to pink and my breasts are starting to produce “discharge” it’s not clear, it’s kinda milky, but not quite white. I’ve been on birth control for a while, but my SO and I are very active.

My next period is due in a couple of days, however the light pink spotting hasn’t stopped. It’s barely enough to even fill a panty liner. Took a FRER today and thought I saw an EXTREMELY faint line but, I told myself I was psyching myself out.

Does anyone have ANY explanation?? Just need to know if I’m pregnant or not..