Could you share the LayOut file? It would make it easier to sort out.
Did you set the paper size to 11x17 in Document Setup? If so, when you export to PDF, it will be set up to print on 11x17 paper. If your printer only has 8-1/2 by 11 paper, though, Acrobat or whatever you’re opening the PDF in will shrink the document to fit the paper.