JoannFran, I'm on Bisoprolol. I went to a cardiologist about my heart skips and he said beta blockers don't always help, in fact sometimes they add to the problem because they slow the heart down, and then it's more likely to skip. That's why a lot of people get the ectopic beats when resting (though not always), because the heart is slower. And it's why exercise can stop the extra beats, as it speeds the heart up and then there's less time during the electrical activity to create an extra beat.
So yes it's possible the propranolol can assist the extra beats rather than you. But they always try beta blockers.
My skips seem to be way less with hrt (evorel sequi), but there are different reasons for everyone. Another thing I learned was that if I was having a bad day (I've had the days where it's every 3rd beat, etc), plenty of fluid and salt and even some magnesium can help. Dr Sanjay Gupta has many you tube videos about these things but I only watch about the ectopic beats as he does talk about some serious heart things as well.
I hope you'll find a route through this that works for you, in the meantime don't be afraid to rest. I actually took a day off work on one occasion because I got so distraught and I 'gave up' and went to bed. You know what, they calmed down.
One other thing, I cannot skip meals or they will start, so the stomach plays a big role as it is connected to the same nerve (vagal nerve).
Hope you feel better soon.