i have a question for anyone who can tell me. i am just so confused about ll this. i am 17 turning 18 in 3 weeks..Ok.

it has been 3 weeks since i have had sex. It wasn't the 1st time me & him have had sex.. my boyfriend and i never use protection and he never pulled out.i have taken so many pregnancy tests. All of them came out negitive, but one had a fainted line.please help. thank you