HI had sex but after I begain to bleed as if my period was starting I felt as if I was on my cycle as well but, the blood never came back after that night and my period is past due.

When was your last intercourse before that night ?

Probably 2weeks ago.

If your period is over a week late then try a pregnancy test using first morning urine. If that test is negative wait another week or two and test again. If that test is also negative then wait until your next period is due. If you miss that period then test again or see a doctor for a more accurate blood test.