unsure about mental illnesses?

i have come to own the reputation of the "weird, crazy funny dumb girl" in class ever since i immigrated to america. when i started dumb and "funny" it was only because i was still adjusting to america and its culture. but after a while, i start to act like that all the time. eversince 7 th grade, i began to feel like i am used to it...i feel like being werid is jsut me. all my friends claim they are my frinds because i am funny and wild. but deeep inside, i am realizing maybe i am only so werid because i wnt attention. to think of it, if i dont act dumb, i will have no frends. i am not pretty, nor smart. in school i act very hyper but at home i jus get depressed. my mood changes constanly from hopeful to very sad. i feel like i am very lost and i dontknow who i am anymore. bbut eventhoug ifeel very bad abut myself, nobody around me think i have issues. do i have mental illnesss? i hope this is not too creepy and thank you.