Is early 30's too early for menopause to begin?

I've been experiencing some odd things in the past 5 months. (approximation) Steady weight gain, regardless of diet and exercise, my disposition has become quite melancholy/irritable, insomnia, strange cravings, and extremely heavy menstrual flow. by heavy, I mean waking to a blood bath and having to change every hour. I've never been pregnant due to ovarian cancer treatment approx. 7 years ago. Any cause for concern?