Implantation bleeding??

I had sex about a week and a half ago and had missed a couple days of pills the week before. We did not use a condom or pull out. I’ve been told before that it may be hard for me to conceive due to some other health issues I have. So I’ve never worried to much about my birth control. I started bleeding yesterday a light pink and very very dark brown color. I having been filling tampons or anything but its continued through today. I slept without anything last night and didn’t bleed anywhere. I’m not sure if this is implantation bleeding or just bleeding from my pill being off. I also am not sure when to test. My period is due at the end of this coming week.