Im a 17 yr old girl and a bit chubby, any tips?

I have big legs, big ass and a pregnant looking stomach(but I'm not)
I want to lose weight fast, I cant run I'm chronic asthmatic
I want to be able to wear a dress nicely as I don't look very good in one

Any help will be greatly appreciated =]
Update: Im vegetarian and i do dance alot which i dont know if that will help
Update 2: Im VEGETARIAN, i already said that
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