@janet26 here is the Mayo Clinic Q and A: Understanding and treating long QT syndrome page:
https://newsnetwork.mayoclinic.org/discussion/mayo-clinic-q-and-a-understanding-and-treating-long-qt-syndrome/
There is also a Mayo Clinic Long QT Syndrome Clinic page that may provide some information for you here:
https://www.mayoclinic.org/departments-centers/long-qt-syndrome-clinic/overview/ovc-20442144
I have no medical training or background but my adopted daughter who is in her early 30s has Long QT Syndrome which was diagnosed at Mayo Clinic Rochester 5 or 6 years ago. We think it is genetic and I don't believe it can be caused by medication but that would be a good question to bring up with your doctor. With proper care I think you can easily live a normal life. When she was first diagnosed she had a Subcutaneous - ICD implanted but after a lot of problems with being shocked due to false positive readings of the device software and many software adjustments she had them take it out. The doctor convinced her to go with a pacemaker instead which I think she has had for 3 or 4 years and is doing great with it and able to live a very active life.

Are you able to discuss your concerns with your doctor? It helped my daughter a lot to talk with the doctor and her cardiology nurse.

You can go to a long QT site run by dr Raymond woosley called crediblemeds dot org. It tells you which meds are not safe for people who have a prolonged QT.