Have they decided it is a giant from your fundus height? Have they sent you for a scan?
Both are fairly inaccurate so I wouldn't worry too much. I was told that DS1 would be over 10 lb and he was only 6lb 15oz when he was born at 38weeks. Danny Devito is pretty small anyway.
Plenty of women have 'huge' babies without any trouble, and plenty of times the doctors are wrong about the size anyway. Try to relax, worrying won't change anything.