I'll chime in.
I used meth for about a year. My usage was 2-3 days at a time, about once a month, but sometimes twice a month. I know for sure the total usage was less than 2 grams, and probably less than a gram, because when I hit the wall I dumped what I had less, and I think it was at least a gram.
I "hit the wall" one weekend when I had a full-blown panic attack, ended up in the ER because I didn't know what it was. I had crippling anxiety problems for probably two months after that. Like, panic attacks every day. Like, if I ate any kind of stimulant, my brain would flip out: caffeine, hot peppers, even cinnamon in oatmeal one time. About six months after I was in the ER, I had another attack bad enough that I went again, even though I knew intellectually that nothing was wrong with me. I just needed to go to be sure.
The serious anxiety lasted for maybe about two years. I got a prescription for a benzo, which helped some. I also had maybe 1-2 shots' worth of liquor or a beer pretty much most days. I had serious anhedonia this whole time. Like, just, nothing felt interesting. I was annoyed with my wife all the time and any time she expressed any kind of dissatisfaction or unhappiness thought she might be going to leave me. I was constantly annoyed at every little thing, like, there are some dirty dishes out on the counter--DAMN IT WHY DO I LIVE IN A PLACE WHERE THERE ARE DISHES ON THE COUNTER MY LIFE SUCKS SO FUCKING MUCH MOTHERFUCKER THE TRASH IS FULL WHY DIDN'T SHE TAKE THE TRASH OUT WHY DO I ALWAYS HAVE TO TAKE THE TRASH OUT!!! Not like I would flip out and rage or anything, just constant low-grade annoyance at every single fucking thing.
I had tinnitus too. It mostly faded, although I still noticed it some times. I had problems with focus, like I would space out and forget about a conference call that my boss scheduled just the day before and that we talked about and I agreed to be on. I had to come up with routines to help make sure I wasn't doing anything stupid like forgetting to leave for the airport to go on a business trip or something. I would stop in the middle of sentences to come up with words. Mostly nouns. "I'm going to go to the store to get.... soda." Not like I forgot what soda was or something, just like I would start the sentence and halfway through I would lose the thread of what I was going to say and there just wouldn't be anything there. I had some trouble with "tip-of-the-tongue" syndrome, where I wanted to come up with a particular word and couldn't. Like I want to say "happy and zoned out and euhporic" but I can't come up with the word "bliss" to express that.
This one time, I looked down at my car's instrument panel and none of the instruments made sense. Like if you were to look at a word in a book and it stopped being a word and just looked like a shape.
It was 2010 when I hit the wall, and by around 2012, I think I was starting to get back to baseline. I remember when I walked out of the house and noticed that all of the stuff I was seeing was making an impact on my brain. Like, you don't notice this when your brain is working right, but you leave the house and it's a sunny day and the birds are singing and the air smells good and the wind is breezy and you see your car and all of that is lighting up your brain. You feel connected with it. But I didn't have that. I perceived it all, but it wasn't lighting up the parts of my brain that feel good about all that. That's the anhedonia. It's literally "no pleasure" but what it really is, is that your brain is just kind of dead to the world. Stuff happens, and you see and hear it, but there's no connection to it. So I would say it was basically two years before I started actually feeling happy again. In that time, I could feel interested in stuff; I could feel engaged. I worked on projects and felt some satisfaction when I finished them. But I didn't actually enjoy anything.
Now, I basically feel fine most of the time. If I use any speed, the tinnitus comes back for a day or two, and I have mild anxiety for the week following, but I'm basically okay. I don't use meth any more at all. The thing is, I don't know how to answer the question of whether any long term damage has been done. Are the effects apparent? No. But I have no way of knowing how I might be different if I had never used/abused meth. So unless I have some acute problem like severe anxiety or tinnitus or whatever, there's no way to say for sure.