This is a good video that explains how a shotgun should fit you and what you should be seeing when it does. He also has a video that shows you exactly what you should be seeing when fit properly, just search through you tube and you will find it.
http://www.youtube.com/watch?v=vteCAoPwn-s
I had alot of the same problems as you since I never knew how it should fit I didn't know what I was truely looking for in fit.
I used a 870 that didn't fit for over 30 years. When I was bird hunting and shooting a box or so of shells it wasn't all that bad. When I started shooting clays with my sons in leagues I really noticed the fit was poor and I felt the recoil especially when I was shooting several rounds. I bought me a properly fitted Benelli Super Sport and love it. I can shoot it all day without the side effects of recoil.
My sons shoot an 1100 and a 1187. The 1100 has some cycling problems with lighter target loads. The 1187 has had no problems cycling even with lighter loads.
Hope this helps.