30 day cycle to 28, to 25 days, to 32?

I am wondering if premature menopause could be the problem. I am 30 yrs old and used to get my period every 30 days, but it gradually got closer over the last couple of years. I mentioned it to the doctor a few months back and she said not to worry unless it was less than 25 days. It eventually got down to 25 days apart and stayed that way for a couple cycles. I lost track with my current one, and realized that I didn't get it yet, when 32 days had already passed. As soon as I realized it, I got it. It is on the light side, so I guess it isn't impossible that I could be pregnant. I am going to wait a couple of days and see if it gets heavier. My question is what could be causing such an erratic cycle (30, 28, 27, 25, 25, 32)? I don't have any new medications or any changes in my life. Could I be going through Premature Menopause? I am married and have not been on birth control for over 6 years, and have not been pregnant since going off of it.