Missed period and on the pill

I'm on the Alesse 28 day birth control pack (I've been on it for two years now) and I took my last pill on Tuesday. I almost always get my period on the Thursday. I'm 31 days in since my last period and haven't gotten anything yet. I had like no PMS symptoms this month, either. I'm supposed to re-start my birth control pack tomorrow but I think I should try a pregnancy test first to make sure, but if I took it tomorrow would it be too early to show a positive if there was one? I'm almost certain it's just because I've been very stressed the past week as I'm in university and had two exams, but you never know so I think I should take one anyways. Should I wait until my period comes to restart my pill or if it comes up negative should I continue as normal?