I am totally not a medical professional but what you describe feels familiar. You obviously have something going on and are trying everything you know to manage it. Kudos! It seems like you have a valid question worth pursuing. Maybe it isn’t your heart but it is something. You want to protect it!

I was told I did not have a heart problem if my chest hurt at rest instead of while exercising, and given nitroglycerin to use should that happen. After eventually seeing a new doc I tried a tablet under my tongue (while at rest). It offered relief and also served as diagnostic. I have used one form or another of nitroglycerin since. Figuring out a schedule helped my nights as well. Protecting my heart was my new care teams priority and took one symptom at a time after that. I hope you are able to prevent irreversible problems rather than to wait to react to them when they come up. Stay persistent!