Fleas after bravecto- am i overreacting?

So my kitten had fleas when we got her in april but we didn’t know ofc until around a week later. We didn’t actually see any live fleas but saw flea dirt and then brought frontline. The day after we saw dead fleas so it worked and we did it the next month aswell.

However around a month ago at the start of june, i found more flea dirt and one singular live

flea when i flea combed her. I called my vet straight away and we collected her prescribed flea medicine (bravecto) which is effective for up to 3 months.

Fast forward to a couple weeks later and i see flea dirt again, a singular dead flea and i just saw a live flea on her right now when i combed her again. I’m freaking out! it feels like it’s never ending. I can’t tell if the bravecto didn’t work or if these are just fleas from the environment hatching and biting my cat and they’ll die before laying more eggs. We treated the house aswell ofc with a vet prescribed spray aswell as hoovering and washing bedding but i guess it wasn’t good enough!

Should i go back to the vets or just continue vacuuming and combing my cat?