at my 37w u/s, logan was 6lbs 2oz....well, I had him a 39w and he was only 5lbs 12oz! Now with my other child I had a u/s at 36w they said he was 5lbs 10oz Had him at 38w5d and he was 6lbs 10oz...Im sure your baby weight will be ok. they could be off by a lbs!
They estimated my baby would be on the smaller side (10th centile) being about 6 pounds 10 ounces and she was 6 pounds 9 ounces. Though she was 8 days early (and they thought she was earlier than that) so she prob would have been bigger than their prediction. She was perfectly healthy too so even if you have a small baby she could still be healthy. They scared me with saying she had IUGR and I freaked out for nothing :)