don't worry too much trust your midwife and specialist. I have had 3 small for dates babies. I never measured bigger than 30 weeks for the last 3 pregnancies.

My DD now 8 was 2.4 kg at 40+3 weeks
DS now 4 was 2.2kg at 38 weeks
DS now 2 was 2.4 kg at 38 weeks.

They were all below the 3% at birth as well.

I also had poor fluid levels but down to 4 at one stage. Plus I had poor blood flow in the cord along with many other things I could list. I had 13 scans and numerous CTG's and my kids are all fine now you wouldn't even tell they were so small. I was also diagnosed with IUGR with all of them as well.