I started struggling a lot with social anxiety in primary school, it was slowly develiping through middle school. It wasn't as bad though and I had lots of friends at that time. Then highschool came. New school, completely new people. I couldn't find myself a place, didn't have anyone to talk to, spent all the breaks alone on my phone. I got bullied by teachers a lot, missed a lot of days to the point where I almost didn't pass. But with the amount of work I was still making myself busy enough not to let those thoughts get over me. The worst came right after high school. I went to the university, first year was fully online. Again. didn't have friends, couldn't find myself a place and then big stress from finals. This was the lowest I've ever been at. I couldn't eat, couldn't sleep, wasn't even able to shower often as my body felt so weak and sore. I had no energy. That was when my suicidal thoughts got very loud, it was very hard to manage. I started self harm, was constantly just in bed crying. I was probably the most awful person to talk to at that time, got a lot of shit for that from my family which probably was making it even worse.
So yeah, overall I started struggling when I was~9, then it kept getting worse and then at the age 16 it just went fully downhill and I hit my rock bottom at the age of 19. Since then it's pretty stable low with some ups and downs.