[JRMichler]

You are starting with bad information. Maximum heart rate cannot be calculated from a formula because everybody is different. There is no such thing as a heart rate over 100%.

The most popular formula for estimating maximum heart rate is 220 - age. That formula would predict my maximum heart rate to be 220 - 62 = 158. My actual maximum heart rate is about 180. I hit 166 this morning during a tempo run. A tempo run is hard, but nowhere near flat out. I hit a peak heart rate of 177 at the end of a 5k a few years ago.

If you need to pass a PT test by running two miles at a certain speed, you should be training at a speed about two minutes per mile slower than that. Your goal is two miles at 8:51 minutes per mile, so your training runs should be at about 11 minutes per mile. Get your training run distance up to at least three miles, and do that at least five days per week. Six days per week is even better. Then gradually speed up to ten minutes per mile.

Get rid of the heart rate monitor and run by effort. Hard enough to work up a sweat and easy enough to talk in full sentences.