Condom was too big

My fwb and I are ALWAYS safe and never had issues with him until tonight. The condom he brought was way too big and I’m afraid he came in me. I did take a plan b to be on the safe side but still worries me. My period app says my period is due in 10 days. Is there anything else I can do? Side note; I didn’t see that it was too big until I was throwing the wrapper away or I would have brought it up while he was there. I’m not sure why all of a sudden he brought the wrong size.