My Dex is 17 and we end on level 11. I'm a ranged battlemaster so I'm planning on getting sharpshooter at either level 4 or 6, with that it leaves me with 2 possible asi so do I either get a a half feat like piercer or skilled and then ASI to 20 or could I get away with dex 18 and go for some other feat like fey touched?

What are your other stats? What species are you?

Keep in mind you could do 2 1/2 feats (3 I guess if you count sharpshooter), still hit 20 dex and have whatever goodies you get from the feats.

I personally feel like if you don’t have something that uses int, wis, or cha than you shouldn’t bother with fry touched (especially if you are playing to 19 and gain the epic boon that allows you to teleport.) I’d go sharpshooter, piercer, +2 dex, and then try maxing out your con. 

Quote from Actionsparda >>

I personally feel like if you don’t have something that uses int, wis, or cha than you shouldn’t bother with fry touched (especially if you are playing to 19 and gain the epic boon that allows you to teleport.) I’d go sharpshooter, piercer, +2 dex, and then try maxing out your con. 

 OP stated campaign ends at level 11. 

what does your character do besides ranged battlemaster stuff? Could you do a feat to help with that or expand on that?