I have several pairs of G by Guess shoes.  I purchased a 9.5 and I won!  The recommended size for me was 9, but, I didn't want to take any chances, especially with a peep-toe.  The sling strap is adjustable, and it fits securely around my heel.  Additionally, I have enough width in the toe area.  No pinching or rubbing.  And, my baby toe is not peeking through the opening on the side.