Which ones? How many? When is it too much?

Well, those are my questions of the day.  There are so many possibilities online for joining groups, selling on different sites and different kinds of sites, etc.  I am presently on Etsy and Artfire.  I love Artfire, thinking about leaving Etsy - takes up too much of my money for too few sales.  But the bottom line is, I wonder how many sites one could manage effectively?  I could spend many hours at the two I have and actually I do.  I keep improving my pictures, adding new tags, adding new listings, moving things around and changing my announcements.  I'd kind of like to add a third shop, but not sure and have overstretched myself in other areas of my life before.  Anyone else dealing with or have dealt with this before?  Got any advice?

Here's one of my newer pieces.  I love using materials from nature.