Can I possibly be going through menopause at 18?

Okay I don't know what's going on... I'm 18 years old. Last year in March I got pregnant (purposefully I'm married and all) then miscarried. Since then, to the best of my knowledge I have not ovulated. I've been testing almost every day for and year and nothing. Not even a faint second line. I don't know why. Then I was on my period, light at first then heavy for almost 2 1/2 months. Then off for a week or two and now I am on it again and have been on it for 3 weeks. I don't understand whats wrong. And I think I've been getting hot flashes. Do you think its menopause? What EXACTLY are the signs of menopause? Any help is appreciated.