HI,
I understand they make standard & long versions of the rubber straps, not sure about short ones. I got mine from Marcus watch in London, and they said that they found the straps work best for most people with a 'long' on one side & a standard on the other. This sounds to me like maybe they think its best that way to make the watch sit better, ie solve your problem.
Im a big chap so I just went with 'long' on both sides & mine sits perfectly on the wrist.
Ring/email Marcus watch I am sure they will be able to help you with a bit of advice if nothing else