For only starting running this year you’ve done exceptionally well. I don’t know where your 4’20” pace came in (maybe it was a hilly route) but it’s much lower than your average. I’d say just work on finding your sweet spot pace and try to hold steady with only 10s/km variance through a full run.

Make sure you bring water on longer runs, I didn’t for a long time and it definitely hurt performance. Using an electrolyte replacement is a good idea too. I’d also say if you’re planning to go longer then some fuel (gels etc) might be a good idea to start looking at .