How did I find out I have Social Anxiety Disorder?

When I found out that I have Social Anxiety Disorder, it was just 6 months ago. And when I got to know that there is something wrong with me, it was in 7th grade. So, I had just started giving speeches in 6th grade, and every time I got onto the stage, my brain flooded my body with fight-or-flight responses like sweating, blushing, tightness in the chest, trembling hands and feet, dizziness while giving speeches, my mind going completely blank, panting, etc. And before speeches, I faced digestive issues like indigestion and nausea, but I still got up and went to the stage. At that time, I usually memorised 2-minute speeches and delivered them. And I gave 10 to 12 speeches and self-introductions etc., but the symptoms were the same every time. But at that time, I had shyness + social anxiety, so by giving repetitive speeches, my shyness was cured, but not the social anxiety. It was still there as it was before. In 7th and 8th grade I gave them, but nothing changed. Every time, the anxiety was the same. But in 9th grade, teachers started taunting me, and in 7th, 8th, and 9th grade I was bullied, which worsened my anxiety and decreased my self-esteem. And now I am here in 10th grade. I gave a presentation this year and it was a mess, and then I cried for the whole night and denied doing it again because I knew I can't memorise a 5-minute presentation and ignore the thoughts that everyone is judging me for the whole 5 minutes. So now, I usually skip speeches and presentations until my CBT.