Implantation bleeding or period ? Help!

My periods are usually heavy and last up to 5 days. My period came but was not heavy at all. It came the 11th and then the 12th was spotty an so was the 13th but the 13th it was barley there and basically over. I took an ovulation test on the 30th of March and it said it was high so we had sex , is there a possibility of this being implantation bleeding? If so when should I test?