Posted: 17/09/2016 at 20:44
Running slowly teaches you to run slowly.
OK that's a simplistic generalisation but try and run quicker for shorter distances. This is why people get quicker when they join a club as a coach will include higher speed "repetitions" into training sessions. Really difficult on your own.
As you are getting quicker as you run I have a feeling that you are not in the first flush of youth; if I'm wrong then sorry
What's your flexibility like? Increase your flexibility and your stride length may increase; only a 1-2 cm increase in stride length makes a difference.