my mom remarried twice too and i never stayed in a school for more than 4 years because of her getting together with my 2 stepdads,and i moved from Austria to Germany to Srilanka (i moved within the country 2 times there) now im back in Austria & im only 16.i left all my friends back there and the guy i was in love with,everything.personally i'll never forgive my mom for this,not just for making me leave all my friends,but for many other reasons too,but u could try talking to your mom about how hard it is to uproot everything in the middle of the school year and that you just don't want to go.i could never do that because my mom and i just don't get along at all,but if your mom still wants to move ask her if you could move at the end of the school year so it wont affect your grades,and being the new kid in school all the time got me really down but after a while things always turned out okay,sometimes even better.you can still keep in touch with your old friends and you'll definitely make new ones too,just think of it as a personal challenge to prove to yourself that you can adapt to anything you want to,that's what i did.hope i helped,good luck :)