Some nice improvements, but you are cut out for 800/1500, not distances. Your 8/15 times equate to low-17's for 5K. The good news is that you are currently very close to 18 minutes (I'd guess 18:05-10 on a track with good pacing), but that is still way behind your shorter times AND YOU ARE DOING NO SPEED WORK.
With decent coaching you could be running with college kids by next summer, no problem. I would even speculate 2:00/4:10 in a year. I ran 2:05/4:20 as a master barely being able to crack 26 for 200. You are strolling into this with 24-second speed.
Just sayin'
Have fun whatever you choose.