How to beat overleveled players?

im at arena 21 and every single opponent i fight against is level 14 with multiple leve 15 troops, while im level 12 with my troops being level 13. its so annoying because their fireball oneshots my troops that shouldn't get oneshot, and their troops which should get 1 shot end up living with a sliver of hp. i have no idea how im supposed to win without pulling out my evo credit card 😭 my deck is OG pekka bridgespam if that helps