kevinr - What help or support do you have for your depression? I am hoping you get some support.
If you are able to walk a short distance, even just a couple of minutes to start with, do that a few times a week or as many times as you can and then after a couple of weeks just add a minute or two on each day, it will be surprising how just a few minutes outside might life your mood. If you are not able to go outside, how about seeing if you can find an exercise app for seated exercise, I am sure there are ones for seated pilates. British Heart Foundation may have something suitable.
I understand the looking in the mirror thing, I have lost a lot of weight in the last few years, yet I still struggle to look in the mirror, I also suffer depression so am here if you want to talk, I think there are quite a few of us on this forum who also suffer with one form of mental health problems or another, so you are not alone.