Safe side?

My husband and I had recently had sex on the 19th, my chance of getting pregnant wasn't till the 21st, and my ovulation day isn't till tomorrow (25th). He did cum inside me, but I was on top when he did. Usually I heard the on top position is a position that isn't very high accurate chance of getting pregnant and that day I had a low chance of getting pregnant marked on my chart. Should I be worried? We have a 11month son to be 1 year old, he wants a baby, but not yet. We've planned to have a second, but not with our little man barely hitting age 1.   Are my risks still high? Or should I not really get al freaked out and get feelings and trick my mind I could be pregnant?