Never done this before

well here it goes..
I'm 19 and I can safely say I don't have much experience in this world so forgive me if I sound dumb or naive. Nothing horrible has ever really happened to me, aside from my parents divorcing but that doesn't bother me much anymore. I work part time and I am a full time student in community college. As the semester has been coming to an end and the holidays approaching, I have been feeling depression intensifying by the week. I am ashamed. I know I am lucky to have a roof over my head, food to eat every day, clothes on my back, and probably a million other things that a lot of kids my age don't have. but I have these...intrusive, nagging, repetitive thoughts. I hate myself. I've done things that I'm not proud of...I wasn't very modest in the past and thats only part of the reason why I feel dirty inside and out. I could honestly go on for a while and say a plethora of negative things about myself and I don't know why. I don't know whats wrong with me. And realizing this stupid cycle of thoughts just gets me deeper and deeper into it because I start hating myself even more for being this way. I feel my boyfriend of three years getting tired of my negativity...and to be honest I feel like he would be better off without me especially since I've done him wrong in the past...I don't understand why he wants to be with me... It just all sounds so dumb, and I just feel really lost, and I don't know why I can't get a grip. I've got four finals in the next two weeks.. I've got a decision to make about my education and how I'm going to go about pursuing what I want in life.. I just feel so much pressure and most of it is coming from that little voice in my head. I don't literally hear voices, I just mean...idk I'm a constant disappointment to myself. jesus, these cycles of thought get so bad sometimes I just blurt out random negative things about myself like "I'm so ugly" or "I'm so dumb" then I get embarrassed and ashamed all over again and this really pisses my boyfriend off...I'm stressing myself out constantly... I don't know what to do, its interfering with a lot of things. I think about dying but I also think about how dumb of a solution that is for something like this. And then I think about just running away all the time, but I have no where to go and thats not very rational either............thats why I gave this a try.............. mostly I just feel stuck, like the track in my head is on repeat and its the most wretched, pointless song in existence.

First of all, Thank You for responding. It really means a lot to me.
Second, I can't tell you how many times I have tried to be positive through the use of notes or daily lists..
Even though they usually get torn up in my fits of self hatred, I suppose it won't hurt to give it another go. Maybe I'll go about it differently this time around...
No, I don't go to any counseling. I've thought about it but I haven't had any good experiences talking to counselors, psychiatrists, therapists, doctors..
But I WILL keep posting because it really does help.