Might not be the answer you want to hear, but if you look at the elite programs since Arthur Lydiard the overwhelming consensus is that training with lots of volume of relatively slow distance in training is the key way to drop your times, even for 5k etc. Building a big aerobic base is what's gonna really do the work for you.

I'd suggest you could add a shorter-but-faster "tempo" run every week, the intensity is usually described as "comfortably hard" - not all-out or painful but certainly harder than conversational pace. Usually 15-30 seconds per kilometre slower than your "race pace" for the same distance. A similar option is fartleks, where you go for a normal easy run but just decide on a whim to go hard for a couple of hundred metres or so every now and then.

Intervals are gonna help too, though they're gonna hurt like fuck and honestly I feel like they're way more risky for ankle injury than lots of plodding distance. Be really cautious with any speed work.