Had check up with doc on thursday, my temp was 97.1. why was it so low? i'm supposed to start my period in a couple days.

Depends on site: Body temperature is different in different body sites; typical sites temperature is taken with a traditional thermometer: rectally, axillary (arm pit), sublingually (tongue). To monitor ovulation, the temperature should be taken from the same site consistently. When taken sublingually, the thermometer should be placed in the same spot.