I want to lose weight.

I am glad it is friday.I went out for a seafood hot-pot dinner with my boyfriend.It was delicious.I regretted eatting so much when i finished dinner.Actually i am trying to lose weight these days.My sister is getting married next month and I will be the maid of honor.I promised my sister that I will would be thinner.I n fact ,I am not fat but they are so slim. I will do some exercise at weekends to burn less (more)? fat. I wish to become much more beautiful ("I wish to" is very formal and less common than "I want to...") .Please point out the mistakes. Thank you very much