Maybe you should think about adopting a different training philosophy. What do you mean by "train correctly"--without interruption by injuries, or by a particular approach?
You say that you were injury prone from training too hard in high school, and from your description it looks like by saying "too hard," you were doing too much speedwork. I agree with others that you try going easier, but I would suggest a period of aerobic development where you are not afraid to push a steady run every day. Not all out, race type efforts, but you shouldn't be able to talk easily either.
It seems the reaction to training too hard is training way too easy. This is what happened in my case. A couple of years ago I was burnt out, doing 2-3 interval sessions a week on top of 80-90 mile weeks (when in previous years I had only done 50 or 60 at most), where even the aerobic sessions were pretty hard. I discovered the hard/easy philosophy espoused on these and other boards. I started running easier to build a base, but the runs were too easy. When it came time to do interval work, I could handle it without getting injured, but it didn't net me the improved race times; in fact, I went backwards. I tried doing easy miles even with a tempo, intervals, and long run; still, my times stagnated. Finally, I recently started from scratch, building a small but decent base (10 weeks) of harder aerobic running every day at about 100 mpw, give or take 10 miles. I recently introduced longer interval sessions and surprised myself with how easy and fast they went. However, this time I did not make the mistake of making my aerobic runs very slow and easy to compensate for the intervals. This doesn't mean I never take it easy, but most of the time when I'm running I'm pushing it somehow--either on a steady run, or an interval workout, or a long run.
To sum it up, it's a matter of experimenting with intensity. Try some different things. You already know frequent interval workouts doesn't work, and you seem to suggest that easy running/"base building" hasn't gone anywhere either, maybe try some higher intensity aerobic running with one interval session a week.