Pregnancy

Ok this may be a stupid question, but I'm asking anyway lol! My period is now like a week late. I took a pregnancy test 2 days after my missed period and it was negative, but I didn't test first thing in the morning as I know you should. So, just wondering if there is still a possibility that I could be pregnant. I've been experiencing some cramps especially after sex, which is unusual for me. Also, been very emotional and light headed lately but I know that could be related to my period. Anyway I just wanted others opinion's before buying another test!