Definitely don’t take my advice over a doctor’s! I imagine that as a cancer survivor, especially, your body may have been through more stuff than most of us here have been through. It sounds like you’re in tune with what’s going on with your body, which is great. Maybe your hormone doc can help you out with the testosterone as well as sleep stuff. Being able to sleep is definitely important.
On the meals, I didn’t mean to start tracking calories or anything, but just set in your mind that your are going to eat breakfast, lunch and dinner, and stick to a good routine every single day. Like breakfast before starting work each day, lunch at midday and dinner around the same time each night, and similar amounts each dinner, for example, rather than a massive dinner some nights and tiny dinner others. All so your body knows what’s coming.
It does all take time, so definitely be patient and kind to yourself, and take the long view.