My life :(

I don't understand why I feel this way.
I mean, an outsider looking in must think I have such a great life.
Atleast thats what my bestfriend Ashlee told me. She told me I have the most perfect life, andd that she was jealous. Is she serious? My life perfect? I highly doubt that. I seriously don't even understand the point of life right now. I'm spiriling downward fast, and I don't understand why, or how its happening. Like four months ago my life was going great. How can things change so fast. For years I was miserable, I guess it started in seventh grade. I was never happy, I hated life. I wanted to die and I felt like this for years, all the way up until the end of my freshman year. And then I met Erik, and for once in my life I felt like everything was going to be okay.
He showed me that life is good, and that everything works out. I was truly happy, but now I'm starting to be sad all the time, and I figured hey I must be having a bad few days, but days turned into weeks, weeks to months. I haven't been happy in a while, I'm not even 100% sure why. All I know is I've been depressed. But the thing is I've always been the girl people come to for advice. I don't let people in, I can't people just tend to dissapoint me whenever I let them in. I don't get the point of handing out your trust to someone, because it gives them the power to hurt you and betray you, I'll never let that happen to me ever again. So I keep everything to myself. But it gets so hard, its so hard right now. I don't know how to explain how I feel. I've made some pretty bad mistakes in this last few months and I've been trying hard to keep them a secret. But then again this gets hard. My heart is shaky, I have a loving, sweet, sensitive, funny amazing boyfriend. I should be estatic, he's perfect. But why aren't I? Why do I get all of these feelings that I don't want to be with him. I guess I'm confused about what I want. All I know is I seriously Am hurting and I have nobody to lean on. The world is one big scary place and I feel all alone in it and it really does hurt. Somedays I have to try so hard to keep my compure, to stay strong, to act happy. Other days I just feel like a zombie. I have everyone fooled. They all think I'm fine . I have this acting thing perfected. I'm not the girl everyone thinks I am.
I've always been a party girl, and probably always will but i think i might have a alchohl problem. I'm not really sure what the definition of a 'alchohol problem' is but i think I do.
Whenever I'm feeling down in the dumps I get drunk, is that bad? All I want is to be happy. I'm trying hard to be strong, trying to take the advice i give to other people. I always tell them to hold on and that things will get better, but how come I don't believe it myself?

I think I need help :(