Missed period???

So I was scheduled to get my period about a week ago now. It's been a full seven days and still nothing... I had a yeast infection recently and took monistat for it (I don't know if that affects your period). I've also been under a lot of stress recently because I just got into nursing school.
I'm going out to buy a pregnancy test today as there could be a small possibility of pregnancy.
I'm just very concerned about the whole thing... any advice ladies?