There's not really a miracle cure for SA, you just have to crawl out of it slooooowwwwwllllyyyyyy. Honestly I'm not surprised that 6 sessions of CBT didn't make much of a difference for you. At least now that you know how to do CBT, you can keep trying to do it on your own. It's weird that there are so few sessions before you get cut off, must be a UK thing.
Personally, I feel that I've slowly grown out of my SA. Obviously it's not completely gone since I'm still on SAS. But I don't freak out about stupid things the way I used to and have become more open with people in general. I've been in therapy for years, and on a couple SSRIs in that time (currently not on anything). I never felt like any of it worked while I was doing it, but I have noticed a change in the way I am now from the way I was in high school or even at your age. So who knows! But yeah, I haven't found anything that created a real "quick fix," as nice as that would be.