This kind of existence clearly pains you and upsets you so that to me doesn't sound like you are just an empty shell. Depression has many faces and feeling completely drained and exhausted and somewhat careless about others are just some of them. Sometimes the brain can become psychotic from depression too.
Can your doctor refer you to some help, mental health wise????? I think you could benefit from talking to someone who has some knowlegde and experience in these things and sadly, a lot of doctors, though very nice and capable of their jobs, do not have this experience. I think that would be a starting point.
Feeling void of emotions and like your soul is missing is not somehting you should just put up with. Nor do i think it can be managed by diet and excercise. While those things can be helpful to some, they are not a miracle cure to everyone.
I think something to keep in mind though is basic self care. What that looks like for you, only you really know. For me it can be proper food, enough sleep and a balance between company and silent or alone time. For you it may look different, but if you can remember what is good for your body then sometimes that is the spark you need to find the strength and courage to ask for help and fight the darkness.
And if you do decide to ask your doctor, be persistent. Even if everything inside you is screaming for peace and for everyone to go away, be persistent. It can be hard getting the help you are entitled to these days. But you have as much right as anyone. Keep talking here too if it helps. We're listening.