A lot older here, 40, very similar HS times.... it seems like the OP had a slow 800m.
His vs Mine:
2:02 1:58
4:26 4:25
9:37 9:38
15:37 15:37
OP, what is your current 5K time? I've dropped from 20:00 to 17:45 in a year with 1600 miles and being out 4 months with a couple injuries. 15:xx seems like a million miles away...