Worthless? Wasting my time?? Never! Not with those beautiful words you used in the first line!
What you described is something I've felt countless times over the past 4 years. I get so tired of trying to get better and always falling back again. The feeling of trying everything and nothing working is beyond frustrating.
I know you hate how you feel but, really, who likes depression? It ruins self-image, self-esteem, self-confidence, eating patterns, sleep patterns, perspective on life, perspective of others,LIVES. If depression were to be brought into the real world, have form and flesh and blood, it would be a horrid monster that even the bravest of souls would cower from. And you are fighting it, alone, because the truth is, depression is something our brains make us feel. Depression is ourselves.
This shouldn't make you feel helpless or hopeless. You should feel overwhelmingly proud that you have been putting up a fight and have gotten this far. Think of how triumphant you will feel when the monster in your head cowers from you. You are brave, you are strong and you can beat this. You will beat this. Don't give up.