honestly, if you haven't broken through the shyness now...well you still have a lot of time!

seriously, the older you get, the more you learn the value of life and don't give a crap about what anyone else thinks! I was rather quiet, rather insecure but that faded with age. I came from a large family that didn't have any money. I came out in my 20's (no, I'm not gay!--just less shy) and then in my 30's, oh my god, my life got so much better! I know technically you're currently an adult but you're still so very young and you're not fully formed yet. you'll get there eventually so just keep doing what you're doing--learning, living.
perhaps what Mommi said may help--anti-(social)-anxiety meds may help. believe that the future holds a lot for you!