Thank you, it's just a little bit worrying
Your fundal height should be the equivalent in cm to your weeks of pregnancy, so if your 31 wks you should be 31 cm however they allow a 2 cm variance so even if your 31 wks it's ok to be as small as 29 cm or as big as 32 cm before there is any need to be concerned :)
In other words you're fine :)
*30 weeks sorry lol NOT 39 LOL
I went to the doctor yesterday and I'm 31 weeks and they said I was measuring 39 weeks also...they said that it's fine as long as it's not 3 over or 3 under what your supposedly week is...so I'm not too worries she might not be a huge baby :)