baby weighing small :( 30 weeks

Michelle • 33 year old from Australia , currently pregnant with baby #4 a boy..miss 7 mr 5 miss 1 and prince due 26/01/17
So I had a growth scan today I'm meant to be 30 weeks but paperwork is saying 29+1 from 6 week scan but my hospital is going by 30 weeks . My boys head is measuring 2 weeks ahead , but rest of body was just a little under . She said his 3.4 pounds ATM but is a little under what is classed as normal ? Now I'm panicking something is wrong :(