Again, I am not an expert, just giving my personal experience with flea battles.
Yes, fleas won't just bite you on your ankle, but if they are in your carpet, that is how they mostly get on you, they will hop to your foot or ankle,(from the floor/carpet) and crawl thru your sock to your skin. Not saying that the ankle is the only place they will bite. It is just more common when the carpet is infested.
Have you treated your closet floor? Vacuum there often as well.
Yes, you can vacume your mattress, it cleans it of tiny dead skin particles that have fallen off of our bodies and any tiny little bugs,mites, bugs,Flea larve,and other living things,(that eat the dead skin particles) that folks can be allergic too whether they are visable or not.
At the time we had a bad case of fleas, my cats,(2 Persians) would jump to the top of the washer in our laundry room and sleep there, cooler on them I suspect. When I did laundry, I found that there was a red stain on the rubber skirt that lined the inside lid of my washer. Those fleas would jump off of my cats and down into the space that is left around the lid of the washer and the poop they left would get wet and stain it. So fleas can go just about anywhere in your house, you have to clean every nook and cranny those tiny little things can get into.
If I remember correctly, Borax works on fleas by dehydrating them, I don't know how long it takes to do that, but it probably takes longer than over night or a week. So how long to leave it down and how often to vacume it up? I have no idea.
It would help you to take a look at the info available on the web, look up life cycles of the flea,how long it takes the eggs to hatch, and the various forms of flea treatments,(the Borax maker may have suggestions and solutions as well!) of what is available to use on carpets and hardwood floors, what is toxic to pets and children and what is not. The more you know, the better informed decision you can make about what you want to use and not and if you decide to go with a professional exterminator, if they are telling you the truth or running up your bill for their profit.
Oh and find out who publishes the websites you visit as some of them are put out by the companies that make the products mentioned in some of them. Self promotion there but some good info as well.
You will have better luck if you become self educated about fleas and you can sort thru things better.
I am sorry I have forgotten so much and wish the stuff I used was still available. It was rather toxic, might be why it is not availablel anymore or if it is I havn't seen it. But I havn't really had to look for it since then either. I imagine there is new flea killers out there and new info too so the info I am giving you was good for 15 years ago
but you need new info!
I hope the fleas all die soon and stop biting everyone in your home!
Abby and me.