In need of advice related to post-addiction feelings

Fifteen year old male sophomore here. I'll try my best to keep this short, I struggled with porn addiction when I was only in 7th grade. Luckily, after a lot of effort I was able to break this addiction, and with the exception of one minor relapse I've been well over 18 months free. However, the minor relapse really did a number to me, so much so that when it happened my mind went into overdrive and I tried to quit masturbation as a whole. Looking back on it, it was a really stupid decision, and while I stopped probably no more than I week after I tried to get away from it, the damage was done. While i'm just guessing here, as soon as I started masturbating I think my mind connected me not being able to stop in the same way it did with porn. Now everytime i do it, I feel this intense feeling of just unidentifiable negativity. While inherently I know and tell myself that its completely normal and i'm in total control, I can't seem to rid or at least minimize the feeling. Combined with the recent stress of school starting and now taking AP's as a sophomore in high school, the stress of it all has really gotten to me and started to affect my performance at school. If anyone has any advice I would really appreciate because as schools starting to really start up with the first unit tests coming up it would be really beneficial to put this all behind me. If anyone has any questions like how I broke the addiction feel free to put them in the comments below. Thank you!