What is the clear stuff in my underwear?

There is stuff in my underwear that clear. There is also a little bit of yellow. I know its wet because I can feel it. It started about three days after March 28th because on March 28th and a few days after that i had a little bit of brown stuff in my underwear. After that I've been having the clear stuff. But I think some of it's pee because sometimes it's yellow. But I never notice it until I feel the wet or I see it when I go to the bathroom. It's not my period because it's every single day. I don't think that's normal!!! My sister got her period when she was in 14 in 8th grade but im 13 in 8th grade. Does this mean I'm going to have my period soon. I'm too embarrassed to ask my mom, sister, or doctor. I'm kinda scared something is wrong with me because I might be peeing myself a little bit every day without noticing it. I'm really scared. Please, please, please help me!