My Rocco was around 3-4 lbs at 9 weeks as well. He is now about 12 wks and i believe 5 lbs..i am pretty sure he will be a much bigger than average yorkie. he is very sturdy, has short legs and a thick, wide body..not to mention HUGE paws that he will have to fill as he grows! so your bentley may be a little on the bigger side, but loveable all the same. Rocco is a sweetheart and so loving to our resident dog Bella
Good luck and i wish you many years of love and happiness with your baby!