Am I going crazy?

I had unprotected sex on February 16th and I’m not on birth control and he finished in me. On this app it said my fertile window was from Feb 15th-21st and it said my ovulation day was February 19th. Since then I can’t sleep at night and I’ve had horrible insomnia. Now, I’m cramping and constipated and exhausted. Also, today I got the sharpest pains in my stomach and thought I was going to poop my pants but nothing happened and the pain went away. Do you think I could be pregnant and when should I take a test? Also, my period should be coming on March 5th.