I am 11 and i am experiencing weird things going on with me ! HELP!?

Hey.. I am 11 and am a girl.. I have yellow stuff in my undies ... having sexual thoughts... va**** hair.. armpit hair.. and i wanna have IT.. i feel weird.. and i dont talk to anyone about this problem.. is it just puberty... and i am scared of puberty TOO.. i feel like everyone is going to make fun of me and stuff.. and im SO shy to tell anyone about this.. what should i do .. is it just puberty?? help me please!