No one to depend on

I can't stand it when I'm alone. I do individual activities, like reading books or playing one-player video games, but I can't seem to accept the fact that there is not going to be anyone who's always there when I need him/her when I'm down. I tried searching in many ways-
1. Parents: No way. I feel disgusted to even stand close to my mom and I'm not too good with my dad either, since I get the feeling that he cares about my grade most.
2. Friends: I'm currently in the toughest year of high school, when everyone is studying hard to pass the college entrance exam coming on next year. With everyone so busy, I'm afraid I'd hold them back on their studying schedule. Besides, most of my friends are "fun" pals, not those "sentimental talk" ones.
3. Boyfriends: No. I'm too busy and I don't see anyone suitable for me at the moment.

I think I'm pretty much out of source. Perhaps I ask too much of others. What I'm asking for is that they need to always (or almost always) be there to listen to my complaints when I'm at the most downpoint. Many people had been my consultants, but they have their own life, too. They'd say that they are busy or they have their own major problems at the moment, too. Sure, I'd accept that and let them go, but I'd be even more miserable. It somehow within me created a misbelieve for people. I don't really trust things others say and believes that everyone will abandon me sooner or later.
But there's one more thing I don't understand. I'm already treating other people with the ways I wish to be treated back. I always keep my cellphone on and with me in case anyone calls and tells me that they want to die. I don't want them to feel deserted, thinking that there's no one out there to help them. I do that because I have experienced many times the pain about not being able to reach anyone when feeling terrible. But I really don't feel that I'm being treated fairly. Nobody listens to me!

Jam it back in, in the dark.