I had sex two days before I'm supposed to start my period and the condom broke

I had sex two days before I'm supposed to start my period and the condom broke. I'm on birth control too btw. I started my period and its heavy and normal. It's the most painful one yet but it gets worse everytime so I don't think it has anything to do with the sex. What are the chances of me being pregnant? I've never skipped a pill. And if I forgot to take one I always ended up taking it with the next one cause that's what the pharmacist said. When is the earliest I could get a pregnancy test just to be sure? But I would like opinions please