To women only please..?

starting from around 2 years ago, i have had irregular periods. i have till then always had regular periods, given a day or two at the most. it started off when i went over my due date for almost 3 weeks, and then after that they werenormal again for months. the last 12 months, i have started to miss a week or two and then the month after normal again. sometimes my periods are really heavy, and last for about 6 days, and other times they are quite light, and last for 4 or 5 days. i went to the doctors for a blood test to see if i had started the menopause, but according to the results, my doctor said i had not started it yet? i have heard of something called, pre-menopause, but i dont really under stand it. my tummy swells up a lot more than it used to, and i get more headaches. i am 49 years old. could anyone tell me whats happening, as at the moment i dont know what is happening in my body, and im confused? thank you.