You lost your job because you weren't talkative enough? Surely that is a bit unfair. Where did you work?
I lack confidence at times, but I have gained a lot since going to university and having to stand up in front of 150 people and give a presentation. I'm not shy, I just sometimes don't feel confident in myself to speak up about certain things, although I am getting better as I am getting older!
I wouldn't worry about uni too much, your first day will be a prime opportunity to make friends straight away. Everyone is in the same boat and so it is easier to approach people. I have never seen anyone at uni without a friend, even really, really shy people. You will make loads of new friends at uni, and you never know they might coax you out of your shell!