Bottom line is you need to get out of your parents house and you know it. You're not depressed. You're ashamed you haven't made the move and too scared to do so.
It's not society's expectations of where you should be that you're trying to ignore. You're trying to ignore your own expectations.
You're unhappy with your situation in life and unwilling to change it.
My situation was similar. In 1997 at 23 I Moved out of my parents house and a year later got married. A year after that I was on the verge of divorce. By March of 2000 I was back at my parents place. Mere months away from turning 26 and divorced, now I'm back home in my childhood bedroom. Saddled with loads of debt in a job that paid well but really had no promise. I was miserable.
Three years later I went to visit an old friend who had moved to Dallas a couple years prior. This was the second time this year that I had gone to see him and I was so down in the dumps on the trip home I couldn't stand it. In January of 2003 I had gone to see him as well and almost didn't come home. August of that year was the same thing. I realized I needed my own life and needed to be out of my parents house. Within three weeks I was out. It was a huge improvement. I had pride in myself again. It took a few years and far longer than I'd have liked it to take but shortly after turning 29 I recovered from a huge bump in the road of my life.
It's never been perfect and it's not the answer to all of your problems but you can sure as hell bet your current situation is doing you no good mentally. You have a place you want to be in your life and you're not there.
Do something about it.