What does that mean

I had a doctors appointment today at 30 weeks, doc measured my belly with that measuring tape. She said your belly is measuring 33 weeks but I’m not concerned about it. I totally forgot to ask her what exactly does that mean because I was pissed off at the ultra sound tec so my mind was else were. I called her once I got home I was told she would respond by noon. But does anyone know what it means to measuring 33 weeks when your 30 weeks I don’t get a dating scan ( i think that’s what it’s called) till 36 weeks.