Well over thirty symptoms have been associated with perimenopause. Most women experience some of them; almost nobody experiences all of them.
The difficulty is that individually, each has other plausible explanations. Tiredness, low mood, aching joints and poor concentration are all things a busy person in their forties might reasonably attribute to being a busy person in their forties. It is the combination, and the timing against cycle changes, that forms the picture.
If you are not sure whether what you are experiencing fits, the symptom check takes about two minutes and gives you a summary you can take to a doctor.