Sister's Wedding

So my sister got engaged about 3 months ago and decided she wanted me to be the maid of honor. Without so much as asking me if I would be part of her wedding, she says "wedding diet starts now, you've got 11 months." I was like "wtf are you talking about?" She said "you have 11 months to lose weight since you're my maid of honor, you have to look good in a dress."

This struck a nerve. Am I overweight? Yes. I wear a size 18. But I'm pretty healthy for my size and eat a pretty balanced diet. I have just always been overweight and never had any luck losing the weight, so I quit trying so damn hard and just started loving myself the way I am. Apparently my sister does not love me the way I am and does not want her fat sister to ruin her wedding pictures.

Is it wrong of me to feel really shitty about how she asked me to be in the wedding and how she wants me to look for her wedding?