You can certainly break 5' but don't the key to be as simple as added mileage.
If you are in an inner city school with limited access to soft ground for training
adding miles on pavement will as likely injure you as not.
A smarter option is to add hill reps and stairs. A 200m - 250m hill could work very well
just make sure not to jog down. As for stairs, ask around and find an apartment or office
building with 8-20 floors. A third option might be joining a gym so that you can have a treadmill
for walking and incline running.
The second mistake I see in the advice you've been getting is that you're training
pace is too fast. It isn't you have relatively good speed side capability for the times you are running
and a faster pace likely feels better. My guess is you could run < 5' on 25 miles/week but those
miles would have to be 6:20s not 8:20s
At some point you have to request you not be doing so much racing. Tripling and quadrupling in meets is just stupid. A common practice with mediocre programs.
Essentially, training for