Unsure

Please no disrespect about this just curious. So my husband and I are currently are not ttc. Lately we have been doing the pull out method, we usually stop a few days before ovulation. Well I was suppose to get my period yesterday , didn't happen. Then today, I only had a little blood. Could that be implantation bleeding or period before the next? I plan on testing in a couple days if it doesn't come in a week. I just want advice.