I had an ablation 2 years ago and had the same problem, within a week I was having episodes again. It took about 6 months for me to finally stop feeling like I was having episodes / checking my HR every 5 seconds. Your doctor is right, just try to hang tight. I know it isn't easy.
I had short runs of SVT, a half dozen to a dozen beats which self terminated for about 2 years following mine. I don't know how this compares to you. The thing to remember is that the pathway remains and only a tiny barrier is keeping it from conducting. Give this plenty of time before calling it a failure.