Just wanted to say welcome, and though I am using a different plan, wanted to stop by because I've dealt with some of what you mentioned.
I only got up to 368 (that I know of, frankly, am sure it was somewhere in 370s) but that was enough with my bad knees to put me into using a cane, being on a short term pain med long term, and planning every time I was up - "ok, get to bathroom, grab this, and this, and a drink", to bring back to my chair.
I had to lean on the kitchen sink to do dishes, because I couldn't stand up for more than 10 minutes, and I was dealing with lower leg lymphedema as well.
My husband was doing a lot of the cooking and cleaning, because I could not.
Please know...when I did lose 216 pounds (yes, I flunked maintenance, here heading back to goal again), I tossed the pain med, the cane, resolved the lymphedema 99%, etc. Life changed dramatically. I did it slow, over 4 years, with the plan I felt I could live with, no meds.
I don't know why it took me so long to do it, but when the switch flipped that I was going to, it stayed flipped.
I wish you that flip of the switch, and know that I do believe you can do this. Turtles do win