Did the Dr explain that this is common is girls your age. My daughter had the same issues, after 3days in a military hosipital, then wearing the halter monitor for 2 days, cat scans, stress tests etc. We went to a Dr at the children's hospital he just said it is common in girls her age, gave her meds, told her she should grow out of it. She did to some degree, she passes out when they take blood, gets a tattoo, or an IV.
I have a problem where my heart goes out of control beating 240 -260 beats a min. They have to give me meds in the E R to stop my heart so it kick starts it back into regular rates. I take a bata blocker to help prevent it. SVT, super ventricular tachycardia