I Had Sex On August 28th 2015 And The Condom

I had sex on August 28th 2015 and the condom broke and now I'm wondering if I could be pregnant my period is not regular I sometimes go a month or two not having one but a week before I had sex I had my period it only lasted 3 or 4 days and it was mostly brown but there was some red so now I wondering if I could get pregnant and if so when would be the best time to take a home test