Very low, need help please.?

I was diagnosed with depression around 6mths ago i take citalapram 20mg, diazepam 2mg. I also see a therapist every two weeks, but i still feel so low it's umbearable.This evening i've barely left the sofa and have done nothing but cry and have horrible morbid thoughts that i cant get out of my head. I'm 20 years of age and rarely leave the house as i cant bare around people. I only go out if i really have to and have ceased contact with my friends, i feel i'm at an all time low. At times like this in the past i have self harmed but right now i feel like i really dont want to live anymore, i really just would rather end it all than put up with this anymore. I thought i was on medication to level me out and make me better but still i'm so down its like a physical pain. I've never tried to kill myself but i've been close to trying. As time goes on it's becoming more of an option, all i want is to feel like i used to. I've tried but its not worked, im not sure how much longer i can last.