I hope this response is not too late, but as someone who has experienced the same condition, and was diagnosed in 2006, I can relate completely I am now 56 years old Coreg saved my life and allowed me to continue to work and thrive. I was treated with the brand Coreg CR ( ER ) extended-release which has worked for me ever since until they created the generic Carvedilol in 2017 which has been a nightmare. Disfiguring rashes, and swelling in the face, eyes, and extremities. The manufacturer is passing off the generic in brand-named Coreg bottles. I could go on and on, but I can tell you a good cardiologist is key. Please have your cardiologist look at this study below link ( It won't allow me to post it so look up the info under the title if you can) and see if he can put you on a good Beta-blocker. I too have had the worst luck finding a good cardiologist, the recent one has suggested I stop taking the beta-blocker cold turkey and take Mylanta or Tums.
Myocardial bridging: A ‘forgotten’ cause of acute coronary syndrome – a case report from the ncbi.nlm.nih.gov pmc articles PMC2733018

My history is similar to yours. Since MB's are congenital and rare, few pediatricians, GP's, let alone cardiologists have much knowledge of MBs. My mother was a doc and she never suspected an MB, thought it was neurological or metabolic in my youth. I could not compete in any sport because I tired too quickly. Abnormally fast for a child, teenager, young adult, etc. My mom had 5 children before me and all were involved with team sports in school and later for fun.
Not me.