Can confirm thst my periods became more irregular/skipped/late from heroin use. Lots of people say,"Oh, it's from being underweight and malnutrition." Which I'm sure is part of the problem for some. However, I'm not currently underweight. I eat decently. Not super duper healthy as it's expensive but I do cook myself and make sure each dinner has protein, veggies, and a carbohydrate.
So that's not all it is.
I am not sure how harmful this is. Though I do worry, since, for example, after menopause, your risk of bone problems rises. So I do wonder if there is a similar risk. I know post menopause isn't exactly the same as what we are experiencing but I can't help but wonder if there are similar effects.
Then again, doctors put women on carcinogenic birth control pills to stop periods all the time, so...
Bottom line...if this is truly something thsts important enough to you, you will find a way to quit. I'm not saying it's easy. It sure isn't.
Maybe try tapering down slowly, see if you can get your use down low enough to where your cycle improves.
If you want better info, asking a professional is the way to go.
You could try to find research papers online about this issue, too. It is seemingly not an uncommon thing for female users to experience.
Good luck to you on your journey, hon.
Peace.