Not ready to run a 400 yet

I thought about running my first 400m today, but the warmup and the first few sprints didn't feel as good as last time, so I opted for a 300m and some 100s.   My foot and knee hurt slightly in warmups, as usual, but improved after a few 100s.  However, due my my shape and the heat, my 100s felt more difficult than they should have, which made me conclude that I'm not ready for a 400m.

Hot day, light breeze, 85º with a heat index near 90º. 

Hoka trainers on

 300m warmup, stretches, drills

50m strider 

2 x 100m on the turn from the 400m start - 14.40, 13.89 

300m - 44.20  / 2 min rest / 100m - 13.96

I set my goal of 43 for the 300m and fell short.  I wanted to run 14,14,15.  But I ran about 14.2/14.5/15.5.   Perhaps I need to go back to 6 days in between track workouts and take the day off before the workout.   Maybe run some hills.  I don't know.  But I still think 60 flat or better is attainable by the Oct. 20th district meet, still 11 weeks away.  I need to be patient.  In my present shape today,  I probably could have run at 62-63 400m.   Since I'm not going to compete this yr indoors, I have a LOT of time.  My form still feels clunky, my left quad tight, which I have to take extra time stretching and rolling, probably due to that hip flexor tear in '15.  I should probably do more form drills, back off to 70% and work on form.... do drills more than once a week during my track workout. 

As Alan T. said, volume is the enemy for the masters sprinter, but I'm going to have to get at least 1200m of work in if I'm ever going to run a fast 400, but not yet.  Maybe by late fall/winter.  600m total sprints today wasn't bad for this early.  The PT grid shows 30 weeks as a tentative time for 'full recovery' from the knee procedure I had.  I'm just past 28 weeks now and still doing PT, mostly just single leg squats.

My weight is good, 142.8 lbs after workout.  Would like to go lower.