Late period, not pregnant?

My period is over 2 weeks late now. I've been feeling a bit off, but I don't feel like I could be pregnant? Like wouldn't I just "know" if I was? All negative tests so I just think I should just wait it out. My boyfriend is really wanting me to see a doctor because he's afraid I really am pregnant or something could be seriously wrong even thought I feel okay. I've tried to tell him that this happens sometimes to woman. Sometimes periods are late for no reason at all. Should I see a doctor just to put his mind at ease? Also, my periods are very regular. 26 day cycle.