It means nothing of the sort. My bump is measuring 4-5cm/weeks "small" and my bub is in the 61.9 centile for size. Measuring bumps is the most stupid way to tell the size of the baby IMHO - too much worry over nothing! Is your baby active and kicking? Can you hear a heartbeat? If so, you have nothing to worry about.

Also, you didn't say if you were tall/short or what size your tummy was pre-preg. Being tall and slim gives you a different bump to if you're short and cuddly! *Grumble-mumble-stupid charts and stupid averages-grumble-mumble.*