I used the straps to mark where I wanted to put the new buttons. (AS SEEN BELOW) Then I marked with a pen where the buttons will be. Then I took off the buttons and cut the straps completely off.
Cut the length and width of the dress. I got a dress of my daughters that I wanted the same length and used it as a guide. The width I kept wider though to keep the same "straight down" style as my previous shirt. MAKE SURE TO LEAVE ROOM FOR THE SEEMS!
My 3 yr old took this pic randomly...so hey!
Here it is at this point... Then I sewed it together and THEN I added the buttons where I had marked, and LASTLY I sewed on the straps.
RESULTS: we were both happy!