Working from home can be a lot more isolating than most people realize. It sounds so good, and it IS good in lots of ways, but I've found that, like you, if I don't make an extra effort to get out it leads to depression.
You do sound depressed. Have you considered treating your depression? It might make the rest of it easier. Sometimes you can just treat it for 6 months and then wean off any meds you are on. Also, you might want to consider finding a low stress outlet that gets you out and about--a knitting class, a book club, anything you might enjoy.
Life is more than weight and weight loss. It sounds like you are putting off having a life until you weigh what you want to weigh. But you deserve a life NOW, not later.
Good luck to you and please hang in there. I really related to your post, as I also work from home most of the time and it all really resonated with my experience as well.