Two day period after unprotected sex could I be pregnant?

[TheOA1213]

Hello! I am a little freaked out. I had unprotected sex on March 16th. On the 21st  I experienced spotting on and off all day It started out light pink and barely anything to bright red spotting then nothing. I went to bed and the next morning on the 22nd I had what seems a little more normal bleeding all day until the evening. Still not as heavy as normal. My periods usually start off extremely heavy to where I'm changing tampons every 30 min to an hour bleeding through all my clothes. Now it is midnight and its super light again. Again this NEVER happens to me. Not sure what to think..... Since it has only been a week now since iv had sex. Anyone else have this happen? Thank you.