(Still in the middle of a move, so not back on duty yet, but saw this, Chicklet, and din't want you to have to sit.)
No, you have no risk of pregnancy.
You do have a chance at a much more normal, relaxed life though, likely with just therapy or even just medication.
I'd see if you can't get your Mom some literature on OCD. Maybe print out some of those pages I sent you to. Really, I'd hate for you to have to wait until you leave home to have a manageable, productive and happier day-to-day life, love.
What state and city are you in? We could perhaps find you a free resource you could get started on your own with.
Don't be sorry -- your paranoia about this may well be something you can't control (you know logcially it's not possible, but if you're looking at OCD or the like, that just doesn't matter) on your own, or by knowing better. So, let's work on finding you a solution. They're out there.
Editor and Founder, Scarleteen
My epitaph should read: "She worked herself into this ground."
-- Kay Bailey Hutchinson