Confused About Heart Rate Training

I logged my longest run so far while wearing a heart rate monitor and I hit a new high...200 pbm!  I'm not sure if that's good or bad!  I think that my run today seemed quite similar to most of the stress tests for determining one's max heart rate.  I ran at a pretty slow pace, roughly 11 min/mile, trying to keep my heart rate below 160 bpm, but I surpassed 160 bpm around the 1.5 mile mark and it steadily climbed for the remainder of the run.  My peak heart rate came while running up a freeway overpass near the end of my run at about 4.5 miles.

Here is the Garmin Connect data from my run:

I'm thinking that I need to go out and get a book on heart rate training because everything I've read online seems to say that my max heart rate should be around 190-195 bpm.  Even if I were to assume that 200 bpm is my max heart rate, doing a 70-75% of MHR long run would put me between 140-150 bpm and I can't even maintain that for a mile at an 11 min/mile pace.  I asked a trainer at Gold's Gym if they can do a stress test to determine my MHR and he told me to subtract my age from 220.  He also told me that my watch was probably wrong about my HR and I should check it, which is probably a good idea.  I was a bit irritated that he couldn't tell me anything else about heart rate training except that I should slow down when running because a ~170 bpm average HR is too high for a long run.  I can't really slow down any more than an 11-11.5 min/mile pace.  It already feels pretty uncomfortable to run that slow.  Most of all I'd like to know if it's unhealthy or dangerous for my heart rate to get so high during exercise.

I would love to hear any suggestions or advice from anyone that has experience with heart rate training.  I also plan to try the local running store, which has a treadmill, to see if they can help me out with a stress test to find my MHR.  I'll keep you posted!

Happy Running!