Hi and welcome to HealingWell.
I am so sorry you are going through this, especially at your age. I was also diagnosed very early on in life (first panic attack at 10, medication & therapy since 14.)
You asked if you need therapy- it couldnt hurt to discuss these feelings with a professional and get a proper answer, so in turn, you can get some relief from the intrusive thoughts that are bugging you. I am mildy OCD and Ive noticed it takes my mind a very long time to calm down and unwind. I think constantly, over analyse things and stress myself even more.
You are not going crazy. The symptoms you have mentioned are all a part of anxiety, which is very real, but very treatable. I dont know if the Zoloft would make it worse: im also on 150mgs of Zoloft also, in combination with Xanax.
Please stay with us here and keep us posted. Hope we can help you. You are NOT alone!