I'm shy in school but when i'm alone or with family i have really great confidence.?

ok so when i'm at school i have friends ..nice ones too but i feel shy around them and i don't speak alot and when i do and start being normal i feel like i acted or said really dumb things especially when im the center of attention for a minute or two ..i just bail out..i feel like i'm that nice quiet girl that sits in the corner of the room looking out the window and saying "hi window hows it going" i don't want to bee that girl...and don't laugh because i feel really stupid...i never was that shy girl at school i was always the center of attention and i never even felt it....(ok i was in america in elementary and then in fifth grade i came to egypt i didn't know arabic that well and i was realllllly shy and everyone be friended me at first because i was from america but after they got bored of me because i couldn't talk or do much..)any way after that they got used to me being the shy girl and left me .....anyway after i got used to egypt and learned to talk fluent arabic i got new friend but not bec i talked to them ....they came to me...i talk a little....i tried to feel comfortable around them but the shy girl in cl doesn't just bust next year and become the popular girl...i guess i got used to it...i want to go back to how i was ...i really do but every time i tell myself i will i end up being the same person ..no matter what i do....at home im just fine and pretty cool too...i want to be at school like i am at home.im really sad right now and need help i need to...to...be me again......please help me :'(