More regularity in menstrual cycle on stimulants

I’m just curious if this is the case for any other women.

When I am on a stimulant, my periods get extremely regular. 28 days on the dot. This has NEVER been the case in my life when off a stimulant. This has happen both times I’ve gotten medicated as an adult. (I took a few years off due to insurance issues, and recently got back on.)

Off a stimulant, my periods are anywhere from 29 days, 36 days, even as long as 60 days in some cases apart. There is no regularity. Getting pregnant with our three children was a challenge because of this and took a while with each because I was having to closely track my cycles to try and catch ovulation.

To note, I’m Catholic now, so we don’t use hormonal birth control of any kind. So it isn’t anything like that affecting my regularity. I’m 42, so I’ve known my body for a while. I’m just curious if this has been the case with other women. My theory is that it removes stress which is caused by the heightened state of ADHD and with that relaxation the body can function better.

Any input?