How do I stop believing my obsessive thoughts around my health?

I need help stopping my compulsive thoughts and worrying

I have gotten maybe about 8 EKG’s within the lest 2 years? I’ve also gotten an echo done, and I got a heart monitor to track my heart over the course of maybe 2 weeks, back last year. Even though I have been to the emergency room so many times because of panic attacks that I thought were heart attacks, and went with a Cardiologist I still obsess and worry. I always think that I am going to develop some kind of heart problem after getting the tests done. Like if they’re just suddenly going to appear/my heart will suddenly have an issue. I especially get nervous when the pain is in the center of my chest + I get a tight feeling like I have pressure on my chest and can’t breathe completely. Please someone share their experience of how they controlled their health anxiety, especially if it’s related to this.

For the past three years I've smoked marijuana nearly everyday. It helped with my anxiety and quieting my brain and helped me sleep. Recently, it began to make me feel more anxious, i would wake up nauseous and even threw up a couple of times which really triggered some health anxiety. I decided to quit because of this and i'm almost 2 weeks out from the last time I smoked. My body is slowly recovering but my brain just doesn't seem to quit it. I went to my GP a couple of weeks ago for a routine checkup and everything came back normal in my blood work and exam, yet that hasn't stopped me from completely obsessing over my health and feeling like (in my mind, not my body) i'm seriously ill- which is giving me extreme anxiety. Because of my reoccurring stomach issues my GP referred me to a GI who I had an appointment with yesterday. He was very unimpressed by everything I said and seemed like everything is pointing to IBS-which is not serious and something my mother also deals with. He ordered some extra tests to make sure I wasn't dealing with inflammation and he said he was very confident that my internal vital organs were a completely fine. I'm still waiting on those test results and his confidence should I have made me feel better but i'm still freaking out. Everybody in my life is tired of hearing about it and I just don't know what to do anymore. I feel like i'm pushing people away. I feel good and like myself when I'm distracted and doing something fun, but mornings and nights and when i'm doing something mundane it's the worst. I feel like I can feel all of these pains and sensations but I have no idea if it's real. I've even started asking Chatgpt for constant reassurance and constantly googling my symptoms. I'm in a horrible loop. I should mention that on top of quitting weed, I also just graduated college, moved back home and my boyfriend and I started the longest period of long distance we've ever had to do so i'm just not feeling like myself at all. My psychiatrist just put me on Zoloft (my vomiting and intense anxiety coincided with when i began taking Prozac again so she wanted me to try something else) I'm only on day 3 of the meds but nausea and insomnia are the two side effects im dealing with right now which is just making my anxiety so much worse before the meds have even kicked in. Does anyone have advice on how to break this cycle of constant checking-i feel like taking a deep breath has even turned into a compulsion.