Have you explored all of the resources that Writing Forums and its sister sites have to offer? On
Writer's Unbound you can find some great writing prompts and Spudley (one of the staff members) has an awesome
Automatic Writing Challenge Generator. Another one of our members,
AuthorSue has a great site offering free lessons. The group discussions you crave can be had here and at Lit.org when you post your work and comment on the work of others. Using the PM system, you may be able to get yourself a few faithful reviewers who will usually have time to help you.
If you spend a few minutes using the search facility I am sure that you will find other resources on WF and some links to quality sites. Google can help as well; there are a lot of sites and forums dedicated to writing. Visiting as many as you can should give you a well-rounded idea of your abilities and anything that needs to be worked on. I do have to say that as far as writing forums go, you will be hard pressed to find one as good as WF.
Please feel free to send me a PM if you choose to pursue your membership here and need anything at all.
--DM--