Perimenopause: how do you know?

I’m 43. My period is usually clockwork.

My last period, I spotted a few additional days, which is unusual for me. This period, I’m now on day 20!! I don’t know what to think! Both are a perimenopause symptom.

I also started using a diva cup last month consistently so I’m wondering if this is perimenopause or an issue with using the cup? Feedback welcome!

I’ve done a fair amount of searching/my own research but wondering if anyone has had similar experiences or can suggest a good resource. The only solid advice I see is if my period is longer than 30 days, I should see my doctor.