Help me understand

Hopefully, some experience runners that track with Apple watches can help me with this question. So My goal is to be able to run 1.5 miles in 12:38 or under as most know that's about 6laps. So my Apple Watch is confusing me because I set it for Outdoor Run 1.5m for 12 minutes and l'll describe with the watch showed since pictures aren't allowed.

Apple Watch: 12:43.98 Red/Green bar 1:53 in the Red 9'53" average pace 18'42" current pace 1.56MI

After reading, the watch I double checked the fitness app on my iPhone for more details now it's telling me

Fitness app: Workout time: 12:43 Distance: 1.28MI Avg. Pace: 9'53"/MI Laps: 5

I was positive. I ran the 6 laps on top of starting it and pausing it in the same spot. Was I reading the watch wrong somehow or are Apple Watches just not good in tracking to the T with this kind of stuff? Last question how can I improve my run to meet goal in 5 weeks?