Dress size confusion!

Has anyone else had trouble ordering dresses according to your measurements and the designer's size chart? For example...I was measured first by a shop that said I was 33-26-35. According to the size chart for that dress (it was a David' Bridal online collection dress that I ended up not liking and returning) I ordered a size 4, which said 34-27.5-34...supposedly too small for my hips. I knew it would be too big but ordered anyways. It was huge and would have fallen off if it hadn't had straps. I've been measured by 2 other stores as 32-26-35 and 32-23.5-35. 23.5?! A store I'm about to order THE dress from says based on 32-26-35 I should order a 4, but I know just like the DB dress, it'll be too big and I'll have to pay more for alterations. Has anyone else had these issues?? I'm going to order a Casablanca dress.