First of all, stop worrying! That won't get you anywhere. You've got to set yourself targets instead of fretting about the "whole picture". Take it step by step.
First step, try something small. No biggie, like take the bread around to your neighbour, smile politely and then it'll be over. One issue overcome, as simple as that! Second, buy something from a shop and pay for it yourself. Ask teachers for homework help even if you don't need it, ask a friendly classmate questions about work...Basically, set yourself daily targets.
I know how you feel though, I really do. I used to be shy and would hate it when people asked me questions. On the first day of school whenever a teacher got us to talk about ourselves in front of the whole class I'd freeze. But I did things to help overcome. I volunteered to be a Peer Mentor, I helped my friend set up a club for nervous Year Seven students, in Year 11 I was a Prefect and now I've volunteered in a PDSA shop.
All you need is to give YOURSELF chances. If you sit in the corner constantly thinking that you're so shy you'll never be able to talk to anyone, you never will be able to talk to anyone.
Just take it small steps at a time and seize opportunities as they come along. You don't need to be shy.
Best of luck