I'm irritated with myself...
Why are you being so hard on yourself?
Because I feel like I've wasted my life
It is never too late to fix that mistake. You still have plenty of life left to live, make it count.
Maybe, but I'm not sure if I'm ready to start over.
If you need help starting over you should ask a friend or family member. You should not however, procrastinate anymore or you'll fall into the same rut as before so do it now.