How do you counter Ander's Sentinels?

I keep building anti-air units to try to counter her swarms of sentinels, but they keep getting wrecked anyway. Am I doing something wrong?

Dont let her build them?, Scout + pressure or rush. If an opponent is putting all they’re eggs in one basket it’ll be pretty obvious.

How do you prevent her from building them? They build out of her main base so you can’t assassinate the building pad and she gets them super early game. And if she or her allies build infantry to counter mine then I am SOL.