Plus size mommy here, baby measuring way ahead?

Michelle • Ttc 4 years
A little worried... Went to the baby doc yesterday. I was 27 weeks 4 days. She sounded a little concerned when she was measuring me, and said I was measuring 32 weeks! Like holy cow!! Thats 5 weeks ahead! (And i know my date of conception was right on the money bc we was ttc and kept up with all meds and shots and blood work you name it.) All she said was he was going to be a big baby! Has anyone measured this far ahead before? I don't want to have to deliver earlier than at least 38 weeks!