i have been in that boat, stuck at low mileage and injured a ton, but recently 2 years at 80-100 mpw without injury. although currently fighting some peroneal problems from not paying attention and getting a little too stressed.
repeating some good ideas others have said:
1. hip strength for sure, also glut and hamstring strength (if posterior chain is weak other muscles - quads and calves - have to take up stress)
2. sleep (9-10hrs/day) and balanced diet (eat enough, including fat)
3. "kenyan shuffle" start to all runs - start all runs slower than your grandma walks and ease into it, first couple miles are just warm up. if you care about average pace then just ignore these warm up miles for accurate reflection.
4. run roads with camber very infrequently, but do go out and run a lot of hills - attack the up and go easy on down (hills will help balance out quad/hamstring strength)
5. body circuit work, do things like burpies, single leg squats, bounding, squat jumps, any type of lateral jumping motions. overall dynamic exercises are good. this was one of the main things that let me increase my mileage.
6. besides slow mileage increase, one way to increase that has worked well for me is to add say 6 miles (so go from 50 to 56 to 62 mpw, etc) to a week, and hold there for 4 weeks before increasing again. only increase 3 times in a cycle (so you could go from 50 to 62 over 3 months and then wait 8-12 months before increasing again).
7. balance life to avoid stress - job, school, relationships, etc. body sees stress and stress and can only handle so much, so if stressful job you'll have to run less.
8. massage and active release therapy (ART). at this point you should go, with your injury history your connective tissue and muscles are all junked up and all that needs to be released. once you get all the knots and scar tissue worked out you should be able to do more. at this point those old injuries are weak points that are going to hold you back. this was another key for me.