Hi Jellyfish18,
I relate completely...since I was in my late teens I have had the same social awkwardness you describe, always worrying if it would go anywhere and always feeling there wasn't really any connection with most people I would meet.
Do you like animals? If so volunteer at your local animal shelter, they are always needing help & people who will give their time and hearts to a charity are more likely to be easy going friendly people. It helps you also to give to others in need.
Other volunteer ideas- at your local library, old folks home, Green/environmental group, with children in some capacity .... basically figure out what interests you and find an organisation that does or has that and contact them to see if they need any help.
If you aren't comfortable with the social aspect of volunteering with people, see if there is any organisation who could use your help remotely... I know of animal charities that need help with computer tasks in my town for example. There also might be some sort of phone help wanted.
Good luck.