I really feel for how you are feeling and if you look back I was the same way. I am just not 5 months post-op and still at times seem to have days that are bad and days that are good. I grieved for a long time and it completely affected my life in every aspect. I did have to go on an antidepressant and it helped. I am off it now and wondering if that was a good idea. I have a nasty stoma which accounts for a lot of my recent bad days. Mine is retracted and so small a wafer will not stay on and I have leaking, skin breakdown, and skin infections. It has been this way for a few months and with trial and error If I were you I would try a new appliance. I tried the Convatec durahesive moldable. It forms a turtle neck around your stoma and if yours protrudes this would probably work well for you. The bag is opaque and aomewhere in the middle in size between the min and reg hollister bag. I hope you can find something that works better for you.
As far as back and belly pain I would try easing up on the waling a bit for now. Your body is healing and recovery. Walking is important, but maybe your overdoing it a little. I swear by my heating pad still....on my belly and back. I also went to a chiropractor and found out that I was severly crooked from over-compensating for my belly.
I still have days of anger and frustration and I felt just as you do. I went on meds for 3 months and I have stopeed them and wondering if this was the right decision. I am still easily irritated and emotional, both which are not characteristic of my personality. Please let me know if you ever need to talk.