Baby measuring large

I'm 33W3D, baby should be around 4.2lbs... Well yesterday he's measuring at 36W6D, & 5lbs 14oz.... & that doesn't make him older than what we thought, just bigger. I know ultrasounds can be off up to a pound, but it still has me worried😕 & to top it off he still has fluid in his kidneys, & they've decide he needs an ultrasound once he's born. But on a positive note, they did a 3D ultrasound for me, & he is no doubt my mini me💞💞