Measuring ahead?

Amanda
This is my 2nd pregnancy. I'm 25 weeks this Friday. But my doctor told me today that I'm measuring almost 3 weeks ahead! She scheduled me for a glucose test and another check up in 2 weeks. My fiancé was a 10 lb baby and so was his first son. I'm just hoping he is a big boy and that I don't have gestational diabetes. Anyone else measure ahead and have any advice?