Hey, I'm 21 here and I didn't even get my diploma before I quit pursuing academics. Depression for me started at a very young age (around eight). Sometimes people take a little longer to get their sea legs than other, and that's alright.

Untreated depression has it's way with a person's mind. I don't believe you're 'retarded' considering that you're writing is effective and intelligent. Maybe if you treat the depression you can pursue something in academics or otherwise, later.