How to convince my parents to let me have a Facebook?

[Maddie]

(((reading is optional))) I'm 14, and a good person who gets good grades and doesn't get into drama or anything, My mom doesn't think Facebook is "safe" because of creepy online people and stuff, though I've told her many times that i would only be friends with people i know IRL and keep everything else private to outside people, and she could be one of my friends to be sure that was the case. I really only want it to keep in touch with some people that I have no other way of communication with (friends that go to different schools or friends that have moved, etc) or keep up to date with bands and stuff by friending them. I'm very responsible and don't exactly see whats wrong with it as long as i didn't get into trouble on it. I've told her all this many times, but she ignores it. what should i say to her?
May I add: i'm allowed to have instagram, tumblr, YouTube, etc., its just Facebook shes concerned with.