I use capstar 2x on each of my kittens but my kitten still has fleas?

Alright so i been having a vicious battle with my two outdoor kittens i took in, they had fleas since they were born. Now i had them since they were 1month there mother abandoned them blah blah. I gave them several flea baths and have killed atleast 20 on my white kitten, never found any on my other kitten. I started to find a few fleas on my rug so i tried bio spot, what a waste of money, still had fleas they all ran to the whites ones face. So i called my vet they said frontline, used it guess what STILL FLEAS. so at that point i spent over 150 dollars on house and flea stuff for them, They then suggested capstar, so i used it...2x each on each kitten like they said. Well like 5 fleas jumped off them dead. A week later my kittens are still itching like crazy!!!!!!! But i never gave them a bath to clean there flea dirt off. I also see them chase things, but i dont see what there chasing? Im desperate for help on what to do next. ive bombed the room aswell. Im not understanding how they keep coming back! They stay indoors and stay in one room thats been borax, flea powerded , bombed , sprayed , DE -_- should i just give them capstar again!? I read people being bitten and i never been bitten and i dont believe i have a heavy infestation because i prob found 20 total so far.