I missed a few brith control pills during that time I had unprotected sex,he did ejaculate inside me, about a week later I am now 4 days into my sugar pills which I should have got my period 4 days ago but instead I had abit of browny blood 2days ago it was a small amount and didn't happen again until today same thing abit of browny blood it was very light, I have slight cramping which feels different to normal period cramps, feeling nauseous which is kind of normal for me but not this much and I've never almost vomited like I have lately, sore tender breast, and today I had heartburn which I never get it only lasted a couple minutes

What's the chances? As I have not been consistent with my brith control ?