Hi! I'm 20 and living with my family as well. Although at first I was a bit annoyed, with time I got used to eating different meals and don't really pay attention to it anymore. In general, I don't think you can expect people to bend to the lifestyle you chose for yourself, it's up to us to develop what it takes to maintain it.
Maybe if they are having something you'd really like, just have a small portion of it together with something healthier, but filling.
For example, I think a lot of people find carb/sugar loaded foods to be triggering, but not really hunger satisfying.
Maybe combined with a big salad that takes a lot of chewing, you might feel fuller after and less likely to overeat.
That way, you get to indulge a bit, but nourish your body as well.
All in all, you don't have any reason to feel like a failure! It's what you are doing day by day that dictates your progress, not just one meal.
And being interested in your health while struggling with depression is something admirable.