Some thoughts based on what you told us:
- Use ideally a measuring wheel (can be bought online or at Lowes/Home Depot) or if you cannot affort it, Google Maps to measure out a course and mark it every quarter of a mile or at least a mile. Take your splits as your run on it to monitor your pace instead of using a GPS watch, as those can throw surprises at you.
- Find the longest distance you can run at 10:00 pace and recover from it in 24 hours, and run it 6 days a week with one day of rest. Do not run slower than 10:00 and do not take breaks. I do not think you really need those if you can run 8:30 mile - this is probably your mind playing tricks on you.
- Watch your diet. Stay away from junk food. Make sure to eat balanced meals with fruits, vegetables, grains, and a moderate amount of light meat. In particular, make sure to get adequate amount of iron. Given your age and some of the indicators you described - difficulty maintaining faster than 10:00 pace - you might be low and need an iron supplement.
- If there are opportunities to race in your area, take advantage of them - 5 Ks, 10Ks, track races - high school/junior high, USATF meets.
- Be consistent and do not give up
More info you can gather so people can help you more:
- Go to the track and run the following distances as fast as you can: 100 meters, 200 meters, 400 meters, 800 meters, 1600 meters - not on the same day, though - give yourself at least a couple of days to rest in between each. One lap around a standard track is exactly 400 meters. There should be markers for 100 and 200 meter start. Post those times - the correlation between your best times in those distances speaks volumes about your potential and conditioning and will allow people to offer more specific and meaningful advice on your training.