People at high school can get me to do anything? I am so gullible?

I am male and 16 and I am so gullible people will get me to do anything. I don't know why but for some reason people start being mean to me and I start copying them like if they want me to do something I will do it to the point were they say that they feel sorry for me and stop. I feel so embarred and humiliated. I have a autism spectrum disorder so that might be the case. I also am relay nice so I am easily to take advantage of.people can get me to do anything. I wonder how can I make them not take advantage of me because I am so easy to