Puberty in girls???

i am 10 and i think i am starting puberty! i think this is what it's called...pubic hair is growing and i am getting buds. i am also getting this stuff on my underpants and it is white...i don't know what it's called but i think it's a sign of a period. i am scared to ask my mom about this stuff because she will ask me: how do you kow this stuff....i just can't ask her because i am scared. please tell me some signs of puberty and please tell me how i can ask my mom about this and how i can ask my mom to buy me a bra and stuff. please help!!!???