Periods???

Well I was doing the deed to my self and I've been on birhtcontrol for 4 months now and I have sex with my man pretty offer and never protect but brithcontrol and I never miss a day or time. But I haven't had since the first time I started. but just now I looked on my fingers and it was a blood clot and sum brown glob? Does that mean I'm on my period and it's normal cuz it's just very light or what??