90+ days no period from age 43 - is it menopause?

Hi, I am now 45yrs old and at day 123 with no period. My irregularities started around age 42, with having two periods in a month, followed by three months with no period. This happened for a few cycles. Then it would return to normal for a few months. Then I started having more of these long cycles of 90+ days with no period. I went 90 days without a period for the first time at age 42. Over the last three years I have had six cycles of about three months with no period. I do get some very mild brown spotting at times, but I have not counted these as periods, as they do not follow a normal cycle. I dont bother dping pregnancy tests anymore because I just figure Im not ovulating! I have been seeing a gyno the whole time, who sends me for regular internal ultrasound tests. He says Im not ovulating but does not know why. He kept saying I was too young for menopause but lately just says it is kind of normal!?. I have never had children. Has anyone else experienced this, and what did it turn out to be? thanks.

im 45 and late last year experienced a period 2 weeks after one, then earlier this year a 41 day cycle and more recent a 54 days cycle, i have always been regular around 28 days until this all happened, i keep being told im too young for menopause aswell, i have however had children, but feel i dont ovulate anymore, i noticed a decrease in pre menstrual symptoms probably around age 42 -43, meaning ovulation pain disappeared along with mucus and periods lighter, 2 days and gone, no symptoms at all apart from tender boobs just before period, i think my ovaries are slowing down and sounds like yours may well be too, if you are seeing a gyno then i guess they have ruled out any other issues, ive also had hormone tests that say im not in perimenopause but these are not always accurate, im just waiting now to see what this month holds.