Finally AF?? Help!

I had a D&C on April 13th after I lost my twins at 8 weeks. I bled for almost 5 weeks, last day being May 16th. Today I suddenly started bleeding again and light cramping, I figured it was finally AF arriving, but I stopped bleeding after a few hours. I wasn't doing anything physical (actually sitting around due to a migraine) haven't had sex recently. How do I know if it's AF? We need to start fertility meds, but how do I be sure it's AF?