please help I'm so anxious

I've been on bc for three years. On April 30 my bf and I had protected sex for the first time in a while. It only later about a minute and he wore the condom correctly and he pulled out. The next day, may 1, I started wiping and it was light pink/brown. Around may 3 it started getting heavier like more red and now it's may 6 and when I wipe there's small specs/streaks of blood. I am supposed to start my period in 6 days and I took a pregnancy test yesterday to calm my nerves and it was negative. But I know it was too early to take one. I plan on taking another tomorrow. I'm really nervous because I'm bleeding but we used all the right precautions. Could this be a side effect of bc or stress. I just had finals and now I've been stressing about being pregnant. Or is this implanation bleeding? My boobs have been sore and I've been having mild cramps. Someone pleas help. If you don't think I'm pregnant what could the spotting be?