Please help!

So last Friday I took a pregnancy test and the results showed a faint line. I waited till Sunday morning to test again and bith test we're negative. I was so confused I went to my doctor on June 1st and she also confirmed with my blood results I wasn't pregnant 😩 I came on my period June 2 but its very light (which is unusual) I go off today. My question is....Is it possible to be pregnant while still starting your menstrual?