Heart failure or something else? I’m scared.

[mickey0524]

I’m 18 I’ve been having these weird symptoms for a little over a year now. My heart rate is really weird when im laying down its usually in the 50s when i stand it can go over 90 and when im sitting its 60-80. Usually when I go out for walks it can go over 100 usually stays at 120 and when i try to do cardio it shoots up to 160-170bpm I get shortness of breath chest pressure slightly blurry vision sometimes palpitations and dizziness, my skin has also become a bit lighter. I’ve been to the ER countless times all my tests come back normal ekg chest xray blood tests. I saw a cardiologist about 2 months ago and had an echo, stress test, and holter done. The echo was normal my heart structurally normal the only thing he was concerned about was that my heart rate was high sometimes. He didnt think there was anything wrong with my heart and thought it was anxiety. I have a history of generalized anxiety I started having it when i was 13 thats also when i started getting palpitations/pvcs. I’m really tired of doctors telling me its anxiety when it doesnt feel like anxiety my family thinks that im going crazy please help im scared i just want to know whats wrong with me.