My period last month was September 7-10th, but then this month it was the 3rd-5th. I have never had a period be 2 days long, they've always been 5-7 days. I have been off the paraguard since June, my boyfriend and I had sex on the 5th, could I be pregnant and that's y my period was only 2 days long? When should I take a pregnancy test

If your period ended on Oct 5th and you had sex on that day, its unlikely you are pregnant or that the sex affected your period. However, since the sex was after your period, you will have to wait a few more weeks. Your next period should be do around the end of Oct. If you don't get it, wait until the second week in Nov and then start testing.

I agree, at this point, you wait and see if you get the next period. If you miss it, then test.