Baby measuring small

Heidi.jowett • 24 years young pregnant with my first I'm pommie (English) been in Australia 6 years :)
Had a measurement today on baby and the midwife said I'm only measuring 25 weeks even tho I'm 27 weeks pregnant 28 weeks on Saturday 
Has this ever happened to anybody if so did baby catch up 
I'm heaps worried 
I was a small baby so maybe she is following after her mummy