anytime you have sex you risk becoming pregnant, but yes, especially since you let him cum inside of you, you can definitely be pregnant.
do you want to become pregnant? if not then use condoms or go to the doctor and get on a form of birth control.
i think you should wait at least another week to test, if you test now then it probably won't be accurate. either wait another week or 2 weeks, pregnancy doesn't happen right away, so wait a while to give your body time to release the hormones (incase you are pregnant) if you do it now you're probably wasting your money.