What doesn't kill you makes you stronger, my man...I'm sure you've heard that old addage before but it is oh so true...I've lived my life by that and, believe me, I've had a lot of moments that didn't kill me.
Never settle on anything man...classes, jobs, women...don't sell yourself short...make sure what you have is really what you want...if not, don't fuck around with it, move on!
You're 20, you got a long ways to go, don't rush...sit back and enjoy the ride.
oh and don't invest in a lot of credit cards!