What can I do? I hate Girl Scouts, but I have to go.?

My mom tells me I have to go to Girl scouts, sell cookies, and do all the stuff they do. Some of the stuff is fun, but I don't like doing all this work and doing cookie sales. I'm terrified of people, I can't stand being around them. I can't speak up for myself, and of the four years in GS I never got any better. I make a lousy sales person, people person, and I suck at everything. I want to quit to spare me the pain but mom calls me a quitter and dad will only be disappointed in me again. It gotten to the poi nt that I'm ready to let myself freeze to death in the winter ind to end this god awful pain.... Please help.