At 27, I think you deserve to lead your own life and live separately. The way you look after your parents is admirable. They got used to it and it won't be easy for them when you move, but they should really understand that you're a grown-up person. I know it's a difficult situation for you, but please don't look at your life as worthless because of it! Moving out will be great for you, it's a totally different feeling. And you will still care and help your parents, so don't feel guilty for your decision.