Hiii! I'm Mariana and I'm 14. Recently I did something with my older brother and would totally do it again

My name is Mari, and I'm fourteen. Lately, it's like my own body doesn't belong to me. It has all these new feelings, like it's tuned to a frequency only I can hear, and it's loudest when my brother Jake is around. He's older, and he's got that whole confident, athletic thing going on, and when he's just being a guy, walking around in a tank top, my stomach does this flip. And then, you know, other places. It's embarrassing, but it's also... exhilarating. It makes me feel all warm and then my underwear gets damp. I try to ignore it, but it's always there, humming under my skin.