What Are The Symptoms Of Perimenopause?

Hi there, I'm 42 years old and my periods are extremely regular. My current period is about 8 days late. I know for certain that I am not pregnant. The last couple of days I have had extreme emotions (anger) over things that shouldn't bother THAT much. Today I woke with a headache and its been with me all day. I never miss periods. Is it possible that this is the first indicator of being pre-menopausal? I don't even normally PMS so extreme emotions are not normal for me either. Should I see a doctor?