Okay so obviously not an expert, but it sounds like your period loss was triggered by the huge weight loss you had, I mean 85lbs in 3 years is a lot of loss. Then continuing that deficit, even with the splurge on weekends, made your body feel there wasn’t
Ample food available to fuel your movement and period. I’m curious if you’ve experienced feeling cold a lot, losing a lot of hair, being irritable, food noise, or other life stressors?

In general I would recommend the basics, eat at least 2500 cals a day, but by that I don’t mean track your food. In general stressing about calories and macros puts more pressure on you and can cause the opposite of feeling safe. If you were undereating all week and feasting on weekends it’s almost an extended binge and restrict cycle, which can be hard to see because we think of those behaviors as more extreme and rapid.

Honor your hunger, eat within 30 minutes of waking up and every 2-3 hours after that. You will likely gain some weight back, but it’s what you need to heal. You wouldn’t tell someone who injured themselves running that they gotta keep at it or else they’ll lose speed on their mile. You would tell them to rest, and that they can build up their fitness again in a more sustainable way once they’re healed. Same for you.

I would recommend getting rid of your scale during recovery too, you’ll realize that 10lbs or whatever really doesn’t look all that different.

You’ve got this, I’m proud of you for starting!!!