Feeling bullied at this stage of your pregnancy is not how you want to be treated. IT's funny how they think they are helping you not to have a bigger baby, but a few days is not going to make a huge difference... I had to beg to be let go 15 days overdue with my first baby in a birth centre, but I was lucky to find a midwife that was prepared to back up my decision. Perhaps ring and try and find someone you can trust that can help you make a decision that suits you and your family.
Go well, and enjoy your birth. FIVE babies, wow!