Got my period 3 times but has been lighter im on the pill and forgot my the day of having unprotected sex i had 2 negative preg test could i be preg?

Highly unlikely: If you have had period(s) since you were last sexually active then pregnancy is not likely, although taking birth control pills can can cause a woman to continue to have periods during pregnancy. Pregnancy tests are very accurate and if you have had 2 negative tests, pregnancy is very unlikely. Woman tend to have light periods when taking birth control pills. Unprotected sex = high risk for STD.