Good day.

May I ask if it’s possible that I am not pregnant if I had a serum pregnancy test on the 18th day after having unprotected s*x and the result was negative, even though the doctor said there was sperm inside my body? It’s now the 21st day since our last, and I still haven’t gotten my period. The doctor also mentioned that I shouldn't be stressed because that day, I was rushed to the hospital due to stress.