On average, one can see about a 1% decline in battery health per month of ownership. You've had your phone 9 months and have lost only 6% in battery health. Thus, there is nothing wrong with your phone as it is operating within spec.
Things to do to take care of your battery:
- Don't ever let the battery fully deplete, which can prematurely age a Lion battery
- Try your best to NOT let the battery go under 20%
- Plug your phone in to charge when you go to bed at night, with Optimized Battery Charging turned on and leave it plugged in all night, EVERY night
- Stop worrying about Battery Health decline, which can't be stopped and is normal for ALL BATTERIES