My mom reads my text messages?

You're just 17 and you're not old enough to say "I pay my phone bill so stay away from my cell phone". She's your mother. She's may curious on what you do as a teen, like whether you have a girlfriend, have sex, etc. She is trying to know everything possible. Just that she's not polite enough to check your texts when you're not looking. My relatives always check my inbox, but I can't say a word. They think I'm in a relationship with a my best friend after they read her texts. I hated it, but it is okay. She just needs constant updates on what you're upto. Talk to her, tell her how you feel when she reads your texts like that.