Hey SarahMC - your situation is IDENTICAL to mine... would you believe Im also 34weeks , and measuring 30cm .. the thing is that in the last 2 weeks my fundal height hasnt increased at all ( not even the 2cm it was meant to ) .. so I had my check up on Monday.. and was sent off for an ultrasound... turns out the baby is as healthy as can be , weighs nearly 2.5kg and all is in order..
The lady doing my ultrasound said that measuring fundal height usually isnt a good indicator of how the baby is growing because every woman develops so differently and every baby is in a diff. position..

so I wouldnt worry , Im sure your baby is OK too dont let them scare you.. I know i was