Jumping Plague

FLEAS! My apartment is infested with Fleas!!!! I absolutely hate bugs, which is obviously why I moved to South Carolina - because it's bug free, right? So of course, when I got to my new home, and there was a mass infestation of fleas, I went crazy. We bathed both cats twice that night, and then bathed the ferret, we sprayed the apartment with "anti-bug" stuff, and put flea medication on the cats once they had dried. That was several weeks ago, and although the NUMBER of fleas I'm seeing has fallen, I'm still finding fleas on my bed clothes, and on the cats. One even jumped on my foot when I was standing in the kitchen making dinner! EW! We've treated the cats several times, we've even done research to get rid of them on the ferret. It got so bad at one point, that we wound up spraying the apartment to prevent further infestation, then put the cats in their carriers, the ferret in a box and sat out back for four hours after setting off a series of flea bombs. (did I mention we set those bombs off at 9 PM?) SO, today, I set off on a super endeavor. I have vacuumed every inch - including underneath ALL of the furniture (all of which I moved myself, as I'm home alone this week) - then put borax on everything, even the upholstered furniture, which I then rubbed or beat into those surfaces, waited 35 minutes, and then vacuumed everything once again. I washed EVERYTHING, dirty clothes that have been sitting in the hamper, the bed clothes, the pillows went through the dryer and even my stuffed animals went through a washing process. I then sprayed the outline of my apartment with the bug stuff - as per the directions - put medications on the ferret and both cats, and then put the ferret in his ball - which he hates, but that's a story for later - so that the borax could sink into his carpeted ramps for a bit longer before I vacuum his cage too. If this doesn't work, and I'm still finding fleas ANYWHERE in a week? Then I'm going to freak. I will no longer know what to do, and will insist that we treat the cats and run from the flea problem. Or perhaps call an exterminator. The problem is: That the infestation isn't actually all that bad. I'm not attacked by several fleas every time I walk somewhere, and I only find random ones here and there on the cats. But I HATE FLEAS. and I HATE BUGS. Please understand, I'm taking drastic measures - like moving furniture on my own at 8:30 at night to get to the floor underneath it - to get to the darn things OUT OF MY LIFE. I hate fleas.... hate them... HATE them... someone please explain to me how on earth they are helpful to our environment, can't we kill them all, please? What animal or insect or arachnid depends on them so heavily that they HAVE to exist? Blech.