I heard you should take 3 blood pressure readings 1 min. apart. the 3rd reading is always the lowest one for me. is that the reading to use?

See answer, probably: There is no hard and fast rule. In the office I take at least 2 readings 20 minutes apart if the first is elevated. The second is often lower. For home measurement the 3 readings 1 minute apart are supposed to be averaged to correct for any inaccuracy of a single reading. But I think it's reasonable to take the 3rd reading as a truer reflection of your BP.