I'm in the same boat as you, personally I'm starting off at the start of season 2
If you want to start after s2 then start reading in chapter 35, but I would recommend reading from the beginning there's only 35 chapters and they changed some things in season 1 but nothing big so it's up to you
Season two starts in chapter 16 of 17 if I remember correctly
Considering if you left off on season 2 I would read the entire manga from the beginning. I also left off on season 2 but read the manga from the beginning just to remind myself what's happening. But the manga and the anime for the end of season 1 and season 2 are completely different! A lot of things that happened aren't seemingly canon or in the wrong place!
I got a question, i wanna read the manga, should I start from the beginning or can I start with the beginning of season 3? It’s been years since I’ve watched season 1 and 2 but I think I still got pretty much everything down. Btw I know that the end of s1 is … considered as never happened haha, am I fit to skip some volumes?