Let's talk about first your family:
twin brother - I think he is just pre-occupied with the things around him like schooling, etc. If you see that he is not busy, you can give him starbucks or something to start a conversation with him.

mother - she seems doesn't know that you still longing for her touch. Maybe she's not aware that a 20-year-old guy will still want a hug. Better start to hug her, appreciate her cooking, etc.

father - find some time to go to his place and talk for you to have peace. But my question is, why is your dad not living with you anymore? Do you think that affects the whole family?

Well, for short, INITIATE to do things. We are living in this fast paced world and sometimes those little things are neglected. They showed their love to you first before so I think it's time for you to show it first now. They might just need a little tap.

About your friends:
So what? With what I observed in your message, seems they just talk to you because they need something from you. I'm not saying all of them.

Talk to those whom you find closest to you. If they're distant, ask why then maybe you have attitudes they don't want, etc.

The right girl will come to you (and good you don't indulge yourself in finding friends with benefits). Just wait. You don't need to rush things. You're only 20.