Period is now 6 days late

Okay so today I had to go get an MRI and my period was already 5 days late now normally this wouldn't freak me out because my cycle changes through the year so it's either late or early but my last period was March 25-29 and the sign said if you think you are pregnant let us know because they have no clue what to reprucussions are if your pregnant and having an MRI so I took a test there and he told me it was negative so I sat in the machine for 15 minutes once the scan was done he said that the second line which would indicate a positive test was very faint but said I should retest because of this. Could I be pregnant?