I know I'm a girl and I know I'm not trans. I used to like trying on clothes and wearing makeup. Now I hate it. Sometimes I feel feminine, but mostly I don't. But I don't feel masculine either. I think I'm still a girl even though I don't feel like one sometimes, because I know I'm not a boy, but I not sure.
Gender expression and gender identity are separate things. Females don't have to like clothes and makeup, lots of females are masculine and others are feminine its okay! Its also okay to be neutral and female just be you! Plus you said it yourself you know you aren't trans just do what feels right.
Thank you. The problem is, a big part of me wants to be a boy but I feel like a girl half the time. I don't know why I want to be a guy. I want to be strong and athletic, and I don't WANT to be girly. It's not really about what I feel. It's about what I want to feel.
It sounds to me like you're fed up with gender roles (and rightfully so). A lot of cis people feel like that, and it's totally fine. Gender expectations suck.