wrong size

I went to a Drug Store yesterday to try some new diapers. Those are cloth-backed Slips in size M-L for Waist sizes between 95 and 140 cm. I've tried them last night and they're waaaayyyyyy too big for me. (I'm a very short and pretty thin guy: around 70-75kg ,or 154-165 lbs at 1,67m or 5ft 6in...