Honestly, I think fasting like anything else is a lifestyle choice. You can do 30 day water fasts every year but unless you somehow integrate the basic fasting practice into your everyday life you will lose any results you initially obtain.
I think what happened is that after your 30 day fast you thought in your mind “I did such a long fast now I can just eat whatever, I’m eating less, I can eat everything” and it kinda snowballed do the point where you completely reversed your results. 30 day water fast is pretty extreme, I’ve noticed a pattern which is normal, whenever you do something very extreme in one direction there is a part of you that will want to go in the opposite direction just as extreme. You didn’t eat anything for 30 days and lost a bunch of weight now you started eating whatever and completely let go.
I haven’t heard of anything like it hurting your metabolism like the way you’ve described. However I’d say do like a 7-14 day water fast if you want and then after that’s done implement a daily practice right away such as OMAD or 16:8 or 18:6 type of intermittent fasting to stabilize your weight and maintain it over the long term.
> “. . .after fasting I ate less every meal of the day”
If you did metabolic damage it was probably done by restricting calories on a daily basis afterwords. I’ve been doing alternate day fasting (36 hour fasts) and some 72 hour fasts throughout the past month and on non-fasting days I don’t cut calories at all. I eat my TDEE (total daily energy expenditure) or above.
Research suggests that RMR actually increases during fasting but I’m not sure to what extent or which length/duration fasting this applies to.
There’s some good info here on resting metabolic rate (or resting energy expenditure) and fasting: https://www.dietdoctor.com/fix-broken-metabolism-exact-opposite