Unusual light period do i need to wait until my next period is due to do a pregnancy test?

No reason to wait: Urine pregnancy tests are very accurate, cheap and easy to do. Don't stress about it. Just do a test. These tests can detect a pregnancy about 5-7 days after unprotected intercourse. If you do not want to be pregnant see your doctor to discuss reliable birth control options.

Pregnancy test: If you had sex since your last period and your regular period is late by 4-5 days, do a home pregnancy test. If the result is negative repeat the test 4-5 days later unless you get a period by then. Use first morning urine and follow the instructions for the test carefully.