I dont know how to dress?

okay im 17 years old the question i asked might sound weird but itd true . Every time i go somewhere people ask me how how old i im apparently i dont look my age ppl say i look more like im 15 or 16 the sad thing is il be 18 next month. im 5ft 1 and its not that i dont have curves or anything the lower half of my body like my but and thighs ... well lets say i got plenty of that.. but im not so fond of my brest im a 34 c but they dont really look it there not so pushed together i guess and its the way my shoulders are shapped so i want to dress more .. well i wouldnt say y but i want to dress better i dress up some times but i usually where skinny jeans and some flats with a really nice shirt.the reason i were skinny jeans alot cause i never find jeans that fit right. and i tried waring skirts and i cant seam to find ant that fit right it fits good everywhere else but whu i turn around my but is just barely in the skirt . and i hate it i dont mind weraring short skirts but i want it to look right you kow and i want to feel good when i dress up and go out with friends i want to look like im actually going to be 18.so anything you tell me would be helpful