When I go to the doctor they usually mention my heart rate is a bit high, but when I'm home it seems to be 84-88 bpm. What is an abnormal heart rate?

60 to 100. Normal HR is 60 to 100, give or take another 10 beats, either way depending on other factors like weight and being in shape. At age 31 you should NOT be concerned about HR unless you have other symptoms.