I did some digging and found a strong lead. Benjamin and Sarah (Boston) Nurse had 5 children, including a Sarah, baptized on December 24, 1727, in Salem. Marriage intentions for Benjamin and Sarah were recorded in September, 1714. Assuming they didn't wait too long to marry, they could be your Sarah's parents. Sarah's first marriage was in 1737, putting her probable DOB not much after 1719, possibly earlier. Hope this helps.