I usually start my period on or rught around the 19/20 th of the month, however, I have not started this month. Is it possible that if I had intercourse on the 13th that I got pregnant and it caused my period not to start? And if so, is it possible that it won't show up in a urine test yet?

Before I answer this question, I have questions of my own that need to be answered so that I can answer you accurately.

What is your age?
Are you on any birth control?
Have you ever been on birth control?
If you are or have been, what kind?
What was the first day of your last period?

These are important questions that even a doctor you have never seen will ask you.

I hate to answer questions with questions, but I can't give you an accurate answer without this information.

I am 23,not on birth control. I was on birth control but not since I was a teen,and it was the pill.My last period was July 20th.