Hi there. Im not a doctor but can offer general advice. Enlarged heart is usually a thing that happens over time. Often High BP can cause it. But there are other causes too. You clearly need investigations to determine the cause. With your symptoms, have you been prescribed any meds? Particularly as your waiting some time for tests etc?? Do you have any other medical condition that could cause it? Like diabetes? Or Adrenal or Kidney issues? Have you ever taken a Diuretic medication? Do your ankles swell? How is your weight and do you exercise? All relevant questions. Have you ever had any Heart tests before, ECG, or Echo or Angio or stress test?
Have you had the full range of blood tests? If I was you and I was getting nowhere fast with this, I would put the doc under pressure to hurry things up. The hanging around will just make the nerves get q=worse. Keep us posted