No need to be disgusted with yourself at all. It's summer. Normally I'd tell people to take summer off to relax and lift weights (NO running), but I now realize you can't make EVERYONE think the same way you do :P. So, instead I recommend that if you're going to keep running over the summer to just keep it low volume, moderate intensity (no short speed, MaxV, or SE work of any kind) for awhile and then come September/October you can really start turning it on and getting ready to run. By then you'll have months of base training in and you'll be in great shape to start really seeing some nice gains in speed. I'm sure you're doing an indoor season (correct me if I'm wrong), so I'd say work on 200m speed during indoors to try to get your pr down, and then outdoors, if your speed is still not in place, continue working the 200m speed, but make sure one day a week you do some endurance maintenance work (SE2) to ensure you can still run the 400m (try running a 400m while strictly training for the 200m….not pretty). I think that with 28.8 speed, you can get down to at least 26 this year and if you do that, then 58 is more than in your range.
Sorry for the rambling :no: Good luck!