Odd Build; Where to go with it?

[Pope Scarface]

So I'm playing a High Elf Acolyte of Apollo Battle Master Fighter 4. I've taken Healer as my ASI at level 4, and Commander's Strike, Rally, and Tripping Strike s my manuevers, and my high stats are Dex 16 and Cha 14. I took archery as my style.

Commander's Strike has been pretty awesome with a Rogue in the party, and with only a multiclass Paladin/Warlock for magical healing, that extra healing per short rest (from Healer) seems like it will be really helpful.

We've got a Champion Fighter, the aforementioned Pal/Lock, and a Thief Rogue in the group (human with the shield feat and protector style, half-elf, and lightfoot halfling, respectively).

Game is expected to go to ten; do you have any suggestions build-wise?

Edit- The only real house rule we are using is 15 minute short rest. Long rest is still 8 hours.

[Inevitability]

There's nothing wrong with taking more battlemaster levels, but if you're only reaching 10th level the fighter class loses a lot of its appeal.

I recommend staying for at least one more level to get Extra Attack. After that, you don't really have a compelling reason to stay fighter (unless you really like Indomitable).

How about entering cleric? The domains can give some very good abilities to use in melee, you get spells, and you'll be able to heal people some more. It even fits with your fluff! There's worse melee builds than a fighter 5/cleric 5.

[Kane0]

Bard is another option after level 5, getting you some handy spellcasting, expertise and inspiration.

Alternatively you can stick in fighter for those bonus ASIs and pick up something like ritual caster or magic initiate to further the background without multiclassing.

[Drackolus]

Personally, I would just stick with fighter and grab sharpshooter and 20 dex. Commanding strike is a wonderful thing to use with a rogue, and one more use is one more use. Inspiring Leader is also great as a pseudo-heal, and you have the cha for it (it's mostly level-based, so don't sweat not having enough cha).
Alternatively, if you set your mind to multiclass, i would go from the left field and suggest mastermind rogue from scag.

[Pope Scarface]

I was looking at Inspiring Leader + Sharpshooter (so taking all Feats and no ASIs). Kind of want to see how "necessary" it really is to improve your prime stat. Although the -5/+10 with a dex of only 16 probably won't work out well.

[Specter]

Level 6 and 8 both hold ASI's, so don't leave Fighter before that. First Sharpshooter to increase your own damage and avoid penalties, after that you decide.