Random bleeding

Hello,

I’m 19 and I’ve been on birth control to regulate my cycle since I was about 14. This past month, for the first time in years, I’m experiencing random bleeding when I’m not supposed to be on my period. I had a three day long period at the start of the month, one week after my regular period. Since then, I’ve had two instances of bright red, heavy bleeding that lasted for about five hours each with cramping. I’m due to start my regular period in a couple days, and I’m feeling my regular PMS symptoms. I always cramp heavily on my period, and often at random times in my cycle with no bleeding. I am sexually active, though I’m very consistent with my birth control and my partner and I are very careful with what days we don’t use condoms in case I’m still ovulating despite being on the pill. Does anyone have an idea of what’s going on? Could it be stress related since I’m currently in the middle of finals season?