Kx 65 or something else !!???!!! need help!!?

ok so im buying a dirt bike and iiii luuuuvvvvv kawasaki ....and im 12, but im the shortest kid in the whole school i dont 4'9 - 4'11 ....and i was looking at the kx65 and ppl say its really small..but the klx110 like on youtube and stuff i see kids smaller then me riding it....i love speed and power thats wat i look for in a bike...so i dont i need help ,, answer quick