I'm glad your grandparents care about you to give you the sofa. That is very difficult for older people to not be able to amble about their own home whenever and however they want.
Part of your problem with money, if I may be so bold to say, is that you seemed ashamed that you don't have enough. Pride? You MUST tell your friends that if they can't pay their way, they can't go. I understand how good it feels to go out now and then, but really, putting that money aside and save it will go much farther, longer. It will also show your grandparents that you're maturing. Why not give it to them instead, in addition to the money you give them for food. Surely you take hot showers and turn on lights?
Go to the library and check out the materials by Suze Orman. She has one just for your age group...something like young fabulous and in debt ??? I forget. She is a financial guru. Used to be a waitress and made herself a multi millionaire and now helps others with their finances too.
Problems --or skills--- with money never go away. You have to purposely make changes for the better, make good habits, or you'll live like this the rest of your life.
AND as I noted, with good financial habits formed NOW, they will carry you securely through your life, and you'll always be able to save or get money for what you want to do (as well as provide the normal little things like rent, food, gas lol)
Hang tight. Have you asked your grandparents for advice on how to get out of this situation?
