irregular periods but I need predictability

Does anyone else experience this?

I've always had irregular cycles, like 27 days, then 41, then 33 and so on. This causes me to spend a lot of time thinking about my period and looking for any possible bodily cues from about day 25 onwards.

When it's a shorter cycle that's fine, but with the longer ones I get stuck in waiting mode at some point and get really frustrated, also because it's not behaving according to a pattern that I could predict in any way.

All of that (on top of PMS/PMDD) can make it really hard to function, sometimes for two weeks at a time.