How do I convince my mom to let me live with a friend? (please help, im despearate!)?

well, im a 13 yr old girl. ive been to like 3 or different schools. im sick of moving, and now im supposed to move AGAIN. my parents r divorced. my mom married this guy, but tey might divorce now blah blah blah. well, the school i went to from 2nd to 6th grade is lets say school A. but, for this year, 7th grade i went to school B. i realllly reallly reallly want to go back to school A but to do that I`ll have to move in with a friend from school A. we`d have to work out some kinks but my friends parents are up for it. but, MY mom isnt. i know im young, but i want to do this. she said i`d miss but i know i wont. oh, and she wants to move 2 hours away! i asked if i could try living with my friend for 3 months, and if it doesnt work out ill live with my mom full time. she said shell think about it but what can i say to put her over the top and really convince her. also, ahe always tells me im verry mature and when and if i live with the friend ill actually be 14 years old. pleeease help me convince her! thanks