Sorry to hear your luck with groups is not going so well.. I know some groups are very active and the admins post daily or every second day, unless they are on holidays or something...others are maybe once or twice a month... depends on the admin and the amount of images submitted.
My advise would be shop around until you find a good fit for your work and expectations.... Look at their activity levels on the top tabs to see when the last work was posted.
Nothing stopping you from belonging to more then one group at a time.
Hope your find one you can enjoy :-)) I admin MOUSE, if you want to check it out to see if your work fits the criteria..http://fineartamerica.com/groups/m-o-u-s-e.html
Cheers, Barbara