Almost 18 but still like a child

Hello I’m (17F)next year 18th. I need a big sister advice,

I still look like a child like my face and my style I want to look older and be more mature…Im tired of people always belittling me thinking Im 12.In tiktok i see teens younger than me and looks so mature and older I feel so jealous no one takes me seriously.I got no one to help me im only child and Mom is away.I still act like a child I need to fix this Girlies out there please help me in the comment section give me advice idk It will be really helpful for me thank you so much!!