The first ablation failed. I knew in six days that the electrophysiologist had not blocked all the extra signals because I resumed a nasty AF and had to be placed on amiodarone, an anti-arrhythmic drug. I sent him an ECG recording by my Samsung Galaxy wristwatch, and he could immediately see that it was indeed a resumption of AF for me. He scheduled a repeat ablation seven months later, and that one worked. Note that, statistically across the field of electrophysiology, the failure rate of first (called 'index') ablations is 25%. So, only about 75% of all index ablations are successful, although there is some range between the best EPs and the average EP.
My HR (heart rate) would reach 140-180 when I was fibrillating. Before my second ablation, the one that worked, my HR would rise to 125-135 when walking, no matter how slowly I was going. It was not fun. Like you are, I was highly symptomatic and didn't feel well a lot of the time. My friends told me I looked grey.
If you have some SVT that comes and goes, a beta blocker or a calcium channel blocker should help to keep the rate low, and this is where a good cardiologist comes in, someone who knows you and who knows the science. If you have an adverse reaction to one kind, ask for the other. It may mean moving on to another, more sympathetic, cardiologist.