I recently had a very light period and only lasted 5 days last week. is it likely that i am pregnant and how soon could i take a test to make sure?

Maybe no. Do a test.: A urine pregnancy test done correctly gives a reliable result 3 weeks after sex (3 weeks after when conception might have happened) or 1 week after a "weird" period. If done sooner, a positive result is likely real, but a negative result may be due to testing too soon, and therefore lead to a repeat test. If a woman gets her normal regular period, then she is not pregnant and a test is not needed.