Do you think it's right for parents to be so snoopy and intrusive towards their kids?

I think to some extent they have a right, especially since you live in there house, but it sounds to me like you have NOT given your mother any reason to be so nosy. Have you tried talking to her and asking her why she doesn't trust you enought to always be in your business. Since you are 17 you should be allowed to have some privacy. You could always be a smart a** and ask her if she wants to go to the bathroom with you and wipe your for you. lol