Oh, 4MeNow. I SO understand where you are! I was EXACTLY where you are: 340 pounds, looking at my mid-forties. I am very, very fortunate that I didn't get as far as diabetes and the other challenges that you face, but I know that desparate feeling where I just can't seem to get it turned around. I wish we lived close enough that I could be a help to you, company for walking, etc., but that's unlikely.
I CAN tell you that there is hope! There is a light at the end of the tunnel! When I started I had many of the same problems that you are dealing with back pain, difficulty doing simple things like showering, getting up from the couch. The meds you're on, while I'm sure they help you in some ways, some of them can make weight loss more difficult, but not all of them, and it CAN still be overcome.
When I started I could only walk for a few minutes. That's changed, and it CAN change for you! When I started I had terrible craving for all the old foods that I'd used to destroy my body in the first place. That's changed, and it CAN change for you too!! I've had set backs, and most people do, but that doesn't mean failure. Quitting is the only failure, and I can tell by your post today that YOU AREN"T GOING TO QUIT! You just need a place to get started and some support, right?
The first thing I would ask you to do is understand that this will not be short, easy, or without a few snags, but it's possible. If I can do it - YOU can do it! you actually already have a head start on me, because I didn't start until after my 45th birthday. See? you already have something in the PLUS column!
And that's the second thing I'd ask you to do. Look at what you CAN do, instead of letting the negative control your thoughts. Easier said than done, because negative keeps trying to sneak up on you. Keep a 'mental broom' handy and keep chasing it off, replacing it with positive thoughts. What CAN you do? If you aren't wheelchair bound, you can walk, at least a little. If you do the shopping, you can decide what food comes into your house.
The third thing I'd recommend, well, you've already started doing it! Get yourself a support system. I honestly don't know how successful I would be at this, if I didn't have these friends here to share with. We all have challenges. We all hit plateaus. We all have successes and NSV's and things that we share. We've been there! We're here to cheer you on when you're going strong, and we're here to help lift you up when you're having trouble. We understand, and the most important thing is having people you know you can count on. Here we are!
I've seen people, right here on this list, go from a wheelchair to a healthier life. I know Michelle, who lives in Northern Alaska without so much as a paved street to walk on, much less a gym to work out in, she's DOing it.
I admire that you are still determined to get control. You WILL do it! Make small changes first if you can. No more sodapop perhaps. No more chips. Use commercial breaks to walk up and down a hallway - but not thru the kitchen!
Most of all,

You deserve better than to continue doing this to yourself, but you already know that! If I can be of any help to you, please feel free to get in touch. You know where to find me!!