I'll tell you a bit about my story, because it relates to heart problems.
I was forced into hospitalisation age 16, after going to an eating disorder clinic inside a hospital. They told me that day I had an eating disorder (well, subtly), and after waiting a few hours for test results to come back in, they said I had to be hospitalised because my ecg (heart reading) was dangerously slow, and I was far too underweight (among other medical things; ketones, severe anemia, vitamin/mineral deficiencies etc). Luckily this was one of the view places in my country with an eating disorder clinic inside a hospital. Many people in there (usually 6-7 at a time) were hospitalised for the same reason; heart problems, too thin etc.
I had a tube down my nose, and the first time I ever had that done was the first day I was hospitalised. I had to be on "bed rest" (i.e. not allowed to get off the bed) for about a week. I was attached to the feeding tube all day. Which is filled with that stuff you are required to drink.
So yes Ella, you have every reason to take any heart issues you have very seriously. There is no need to be alarmed, but DO NOT hesitate to seek more advice from health care professionals if you feel weary about what's happening to you. My mother was turned away on numerous occasions to get someone to see me. Meanwhile, I was almost dead. If people turn you away, it's not your fault. You have every right to look after your own life, and it's not your fault if medical professionals out there don't take you seriously because of your illness. Medical professionals screw up. Now is the time to take the best care of yourself, and make sure that you put yourself in places where your concerns are met adequately, even if it means seeing other people and being turned away.