So cross with myself - stayed with friends over the weekend and left the damn thing at their house. Went to buy a new one yesterday (amid much hysteria and distress) as I really needed to test this morning as suspected it was going to be OV day. Especially important this month as am meant to be calling my doctor when I ovulate to book blood tests for 7 days later. My temp has not gone up this morning (on the new thermometer) but I have no idea if this is because (a) it hasn't actually gone up or (b) because the new thermometer just gives different readings. How much discrepancy would there be likely to be between two BBT thermometers, do you think? Thanks!