Dress Choices For A Wedding

OK, the blue dress?  My step daughters wore it to their college graduations, I LOVE the blue dress, I need blue shoes.  The black dress?  I bought it when the son that is getting married  this weekend graduated from high school.  He's 27 now.    I have stilettos with ankle straps that I might wear with the blue dress, they are black though.  I do have better shall we say undergarments to go with the blue dress.....OK, I didn't have on undergarments....
I'm thinking the blue dress?  I have one that is big print black and white but I'm just not into big print....it's a morning wedding outside and it's supposed to be 95 with over 100 degree heat index.....I am going shoe shopping Fri probably so maybe I'll find something else.  My computers are getting so outdated though they won't open certain things.....$100 not spent on a dress and shoes is $100 toward the computer right?
So do I look like an aging slightly chubby slut in the blue dress?  The black one has tiny tiny little polka dots btw, I LOVE tiny polka dots.....and my knees aren't that weird, it's the light I swear....so what do you think?
I don't know what the camera does, I'm taller and skinnier in person......