Worried about measurements from 12wk scan

Hey Everyone, I am probably overreacting (at least I hope I am).......anyway...... we had our 12 week scan yesterday and because I was curious I got my notes out from when we had little man - I just wanted to compare the NT measurements.  Last time they were 1.30mm and  this time they are 1.20mm so I am fine with that bit - but I looked at the CRL and BD.  When we had our scan with DS it was dated 13+1 and CRL was 70.0mm (50th centile) and BD 23.80mm (slighty over the 50th centile).  But this time we are 12+2 so I know that's 6 days earlier but CRL is 57.2 (39th centile) and BP is 18.6 (22nd centile) so I am freaking out now.  With DS I did have morning sickness and this lasted 8 months and I was sick after prettty much every meal for the first 3-4 months but somehow he seemed to always be on the 50th centile and he was born a healthy 8lb13oz' (2 days overdue and a fantastic birth although i lost a lot of blood - apparently more than a hemerage) and had an internal tear so 2 sets of stitches) - but he has always been just above the 50th centile every time he has been weighed.  I haven't taken him recently but it's obvious from looking at him that he is tall and solid lol. So i'm worried now that these measurements being so much lower than the 50th centile is just not good and the amount of sickness I have must be having a massive effect. They also noted on the print out of results 'LT kidney noted' - this can't be good??? When she said "and there's a kidney" - DH asked if that was normal - and she laughed and said "yes" but then put that on the notes and told us she had noted it because it was in a lower position than normal and for them to keep an eye on it. I'm worried that the amount of sickness i've had is meaning the baby isn't getting enough goodness.   I'm sorry to have gone on but I am really panicking now.  I just want the downs results to hurry up in the post as we had the booking bloods and downs bloods taken yesterday aswell so at least I know about them but I need to know that these results are 'normal' or that someone else has had similar?   Thank you so much   x