FLEAS!!! I really have tried everything!?

When I had a flea problem I vacuumed all the house as you have already done, and bathed my cat, then I put some Frontline PLUS on took the cat out and then used a spray that you put in all the house and left with my cat outside for a couple of hours. I kept using frontline for 6 months which at that point I was sure there were no fleas. I stopped using frontline and still never got more fleas. But that was because I had an indoor cat. Now I got a dog so therefore I am protecting them both with Frontline plus and I have not seen a flea.