If you think about it logically, our fertility starts to drop around 35 and off a cliff at 40, so the changes are happening, it's just that we don't notice them until they reach a certain point. I have tracked back and my symptoms became noticeable at 46 and I would say that is a pretty common age, menopause on average happens at 51, thats a full year without a period (2 years is considered menopause if pre 50) so 5 years before makes sense. I'd like to see 40+ quoted more in the media for peri rather than 51 as too many women won't accept that their symptoms could be menopause until they are 50, if they are under 50 they will tell you they are too young for their insomnia/anxiety/weightgain to be menopausal symptoms. Not educating yourself on the myriad of symptoms before they hit like a train can be awful. I thought it was all hot flushes and I've yet to have one, turns out my Mum didn;t suffer from them either and I've also dodged the vaginal dryness bullet to, another one my Mum didn't get. I've got the midrift podge and my boobs are bigger but nothing too dramatic as long as I don't live on cake.
Bless you, I'm so happy it's worked for you, doesn't solve the problem but makes it a little easier to bear. I found the same with symptom tracking, when I looked back it was probably 2 -3 years of minor symptoms, remembering conversations where I had wondered why I wasn't sleeping, or why I wasn't driving my business forward. I can remember getting a new member of staff and every idea she had I shut down, I actually said to her I felt sorry for her because I used to constantly be evolving my business and moving forward and now everything was nope, nope, nope