I think I can relate to what you are going through, and yes, it is a sad and lonely place to be. I don't believe you are cold-blooded - particularly given you share a good relationship with you mother and sister, and, despite thinking you don't like your friends, you do want to have friends.
I think perhaps you need to develop some skills in being assertive so that you can begin to be yourself around your friends and start to express your needs to your friends. Perhaps it is that your friends don't know what you want. They cannot know what you don't tell them. The reason you probably have a close relationship with your mother and sister is that you are comfortable with expressing your needs and feelings with them.
Take pride in the fact that your friends come to you when they have a problem. You must be a good listener and they must appreciate your advice. Feel good about yourself when you are able to help them. But do the same in return. Reach out to these people when you have a problem or need help. They will most likely appreciate that you have put your trust in them. Give them a chance to help you in return. That is the reciprocal nature of relationships. It's not easy to ask for help and it takes a lot of courage. But give it a go. It feels good to be on the recieving end of loving kindness. I don't believe it is humanly possible to give and give and give without receiving. I suspect you are burnt out from doing this for so long and from not expressing your needs and wishes. You will replenish your energy to start giving again by allowing yourself to recieve.