It's up to personnel preference to how many pages are in a webcomic episode. Whatever works well with you.
I personnel found that a page per episode works well since it gets more eyes on you instead of updating the one and only episode, since it gets you on the new released section of either TAPAS or Webtoons. Much more views doing it this way, plus it doesn't get your readers feeling too overwhelmed with a massive story that seems to continue forever..
As for panels per page, I say just do an experiment with the dimensions you are already using. Check it out on your phone or your computer, and if it's unreadable, change it up and re-upload it to see if it looks better. You can always delete your test, plus its much easier doing this instead of having to muck around with a proper comic page.
Check out how others handle panel sizes, you can always learn from different peoples layouts.