How long does ringworm last?

Hi everyone, I have two foster kittens that have ringworm (they had a really bad case of it, however, I think some of the hair loss was mites and I believe their previous owners dipped them in pure bleach or another chemical - this is what my vet suspected as well.) 
Disgusting I know, but anyway. I took them to the vet as soon as I got them as I suspected ringworm. The vet wanted to do a culture first so she gave me shampoo for ringworm. I used the shampoo for about two days until I got my lime sulfur dip. Then I quit the shampoo (I have heard that shampoos aren't the best idea) and I have used lime sulfur dip at 8oz to the gallon every 5 days. 
I wash their bedding probably daily, their bowls are washed daily and their meals are given on plates I throw away. I put Lysine in their food to boost their immune system and I have been giving this since I got them. I also put some taurine but I don't think that helps with ringworm, I just give this because one has a flat chest and the previous owners fed them dog food...
I bleach the environment daily and spray the walls and everything with lysol and F10 (a disinfectant vets use in Australia). Two days after their dip I spray them 2-3 times a day with fungisan or put colloidal silver on them, I used to put lamisil on them however, I heard this is not very effective so I don't do this any more. They are, however, on the oral version of lamisil (terbinafine) and have been for three weeks this Friday. They have had ringworm for about 10 weeks I am assuming as their previous home said they have always been missing hair. I have been treating them for just over a month.

I have a vet appointment this Saturday to have a culture grown to test if they are still positive for ringworm. My question is, how long does it normally take to treat? I don't want to bother with a culture if it is not likely they are over it yet. Their hair seems to be growing back and the hair around where the patches were have turned brown...
Thanks for any help you can provide  I want this to be over!

I think it depends on a lot of factors... a small lesion in a single cat, treated with antifungals and very diligent environmental decontamination could be cleared up in 4-8 weeks. The spores can survive in the environment for something like 18 months, though so make sure you decontaminate a lot! If your cats are re-infecting themselves and each other, or if they are immune-compromised, it could take much longer and in some unfortunate cases the infection can become chronic. If you feel confident about environmental control, are using all the right meds (sounds like you are), then think about what else you can do to make them stronger to be able to get over the infection (diet, stress, concurrent infections, etc.).

I hope you kick it out ASAP!!!

Tabitha