I don't believe that anyone, not even an expert, could/would/should answer your second question...when will it stop? You are quite apparently still paroxysmal, meaning your arrhythmia stops on its own before 7 days have passed while in continuous arrhythmia. That's a good place to be if you must have an arrhythmia. I'm speaking mostly about atrial fibrillation (AF) and I claim no enhanced knowledge or understanding of other arrhythmias (I believe there are 15).

Your devices show normal sinus rhythm, so you have what is called a 'tachyarrhythmia'. Still technically an arrhythmia because its an abnormal rhythm, but it's still sinus. Your heart has multiple quickly repeating beats on what we call a 'run'. Quite often tachycardia and premature atrial contractions (PACs, which fall under the general rubric of 'supra-ventricular tachycardias'). https://www.merckmanuals.com/professional/cardiovascular-disorders/specific-cardiac-arrhythmias/ectopic-supraventricular-arrhythmias), arise from catheter ablations. Even flutter happens to some patients treated for atrial fibrillation, and it's usually easily treated....comparatively.
https://my.clevelandclinic.org/health/diseases/22152-svt-supraventricular-tachycardia+/8*752
Catheter ablations have, across the average of electrophysiologists practicing everywhere, about a 75% chance of succeeding, meaning you go a full year with no treated arrythmia. If you have the same arrhythmia as before, and it is just now three months after the 'blanking' period, you are quite possibly an ablation failure, but your EP should be the one to say yay or nay. He/she will be the person analyzing your ECG, not me.

Lastly, the heart is continually looking to establish new focal points, or re-entrants, for the extra cells that are causing the dysrhythmia. So, maybe further catheterization is in your future...again, your EP will be the one to tell you.

If it's another issue, that has to be established via tests, formal ones. If it's the return of the same type of arrythmia, then I would think it's just a new growth of 'node cell's that are substantial enough to want to begin to send out their own clarion call for the hear to beat to their tune. Except that their tune is out of synch with the SA node and AV node.

This is disappointing, quite obviously. Happened to me with my first ablation...I was in hospital six days later with a runaway heart. I had to go on amiodarone for almost ten weeks, but a second ablation six months later did the trick for me. Second ablations have a somewhat higher probability of succeeding in nipping the extra voltage, about 85% across al EPs. The very best EPs do a bit better.

I hope that helps. Please do contact your care givers and experts and let them know what's going on. Also, HOW YOU FEEL is going to let them know you need relief...and soon, please.