What is the best yamaha dirt bike for me?

im a girl, 15, i am extremly small 5 foot and 97 pounds, and i have rode before, i stop riding for 3 years but i use to race all the time. i want a yamaha because that's what i had before. i plan on using it for track racing as well as some trail riding. i think i want a 125 but im not sure. oh and is there any additions that i should add to the bike to make it better. thank you :)