My baby was transverse lie up until 36wk and i measured small by a few week all along. I was scanned at 38wk and baby changed position but still measured small, was told to expect small 4-5lb baby. Bubs was born on due date at 7.11lb... So i really would not worry!!
I was told I was small for dates too with DS1. I frantically Googled it and got into a state, only to be told when I went for a scan that all was fine and that measuring the fundus is notoriously inaccurate!! So don't worry yourself about it (DS1 weighed 7lbs 6 when finally born). If they are worried they'll scan you, it's another chance to see the bub before he/she comes out, but don't stress, more than likely it's nothing x
I am 30 weeks and having seen the midwife, was told I am measuring small, but she wasn't worried. However, that, coupled with literally everyone telling me how tiny my bump is made ME very worried. So we paid to go for a private scan. £180 and 20 mins later, I left after being told that baby is bang in the middle of all measurements and I have nothing at all to worry about!
Saw the consultant this morning and bump measered 2cms bigger than yesterday. She also said he is well down (not transverse as the MW thought!)and doesn't feel small, but wants me back again in two weeks to have another check.
I shall be surprised if he's small, since his brother was a 9lber who measured bang-on for dates!