Nothing is wrong with you. Chin up. It's human nature to second guess and be apprehensive.
Nothing is wrong. It's called growing up and we've all been there,.
I've been there and a lot of others probably have too. I'm sure you've made a lot of good decisions and a few bad ones as well, just like the rest of us. Try to separate the good from the bad and don't focus exclusively on the bad ones. The feeling you have right now will pass. Trust me, it will. Just give it a little time.