How do i get my armpits to stop sweating?

I am a 13 year old almost 14 year old girl and i will be sitting in class even in first period an dmy armpits will start sweating makin big maks on my shirt and u could tell that i am sweating. Its been like this since i was 12 and it is annoying embaressing and gross. None of my other friends have it like me i dont know what to do. Does anyone have a suggestin?