exporting to pdf - smaller size file?

Hi - I have a 22 page e-newsletter that I want to convert of PDF for circulating. I have down sampled every bitmap in the document to 72 - 100 DPI. The Coreldraw file is 5mb. When I export to PDF - using low jpg, converting all text to curves - the PDF file is 20mb. What am I doing wrong and how  do I get this file less than 2mb? OR do I have to redo  it in WORD or WP? Thanks.