Would rather see 60-90s but that should be pretty dang close to your 5k pace.
The real issue I think is that most 15:00 5K people running 6x1K 12 weeks before the season are not doing it all out, but are running it at something like 10K pace with shorter rest. So there's a decent chance that you are in 15:00 shape -- and a very good chance that you ran the workout harder than you were supposed to.
Totally missed that -- 12 weeks out from a 5k it would be common to do something like 6 x 1k off of 2:00-3:00, repeating twice during the cycle on something like 90s (halfway through the build) & 60s rest (1.5-2.5 weeks out).
But I agree, now is the time to try to get stronger. Tons of speed but that 3k is light years away from your 400/800. As much as it's gonna suck, forget about 5k pace. Do 10k-half marathon stuff. 8 x 1k off of 1:00 rest. Build to 12 x 1k. Slightly slower (threshold type) workouts with good volume will get you ready for cross.