Worried about fundal height?

FTM here & a little worried.

Dr said today that my fundal height is 3cm behind, I'm 33 weeks exactly, so that would mean I'm measuring 30 weeks.. is that bad? He didn't say anything.. just said I'm 3cm behind.. has any mommy's been 3cm behind & went on to have a big, healthy baby?

I'm already worried that baby isn't growing like he's supposed to and that he's behind.. I told my Dr about that concern, and he's doing a growth scan next week for me so my mind will be at ease about it, but I'm still worried about me measuring behind..