As for baptism just say that you will not get baptized because you fear being disfellowshipped. Then ask them point blank if you were disfellowhipped would they stay in contact with you and talk to you....if they say no....then you say no to baptism because you value your relationship with them so you aren't ready for baptism.
The young people ask book says that youth that marry under the age of 25 most likely divorce. So, baptism is an even more important step that should not be rushed. Also, don't mind that example they use about the fear of getting a drivers license doesn't scare you.
Maybe you can get a part time job and make friends there. If your parents ask why say you want to give a little more monetary donations to the world wide fund.
And
DO NOT GET BAPTIZED!!!!!!
Flip the script and say that when people pressure you to do things it makes me not want to do it at all like ever. That should scare them and make them back up some.