Think about the inner values that you have. You mention, you want to make a contribution to the society, and to be a good grandson. That's already a lot! You could start by making really small contributions, it does not have to be world-changing to make sense. Just picking up trash or tending a garden would be a good start.

Take care of your other needs – try to eat well, sleep well, move enough, get social support (as you are doing now). And, as others say, get a therapist that you can work with.

It may take some time to work things out. But it's okay. Just see it as growing and maturing.