You're hitting maybe 20 miles/week? 25?
Decent PR for the volume you do.
You obviously are committed and have a reasonable amount of natural ability.
Every morning, go for a 5 mile jog.
Read up on what Jim Ryun was doing in the 60's.
Let him inspire you.
You can hit the fast stuff, your mile is very good
but could be even better with a bit more volume.
Your 10x400 session is very good.
How old are you? 16? 17?
You could run a 4 minute mile within a year or two by upping your volume.
Do 5 miles easy each weekday morning.
Get in the habit of doing it.
Not easy to start. Maybe only 3 or 4 days your first week.
Before you know it, you'll be getting out the door for an easy 5 without breaking a sweat.
Get 10-15 miles in on Saturdays, even if you race.
Sundays, do an easy 5-10.
That would bring your milage up by 45 miles a week to where you are approaching 70.
Your tempo/faster runs are fine, you can start them out with an easy 2 miles and tack on another 3 or 4
at the end. Get the idea? Turn your tempo's into 10 milers with a fast few miles in the middle.
Now your up to 80/week. Sky is the limit for you.