I meant to also say that STD specialists don't typically manage patients like you. In my STD clinic, we refer all patients with such problems to dermatologists. So I would reemphasize my suggestion that you see a dermatologist if you have not yet done so.
Welcome to the STD forum. I'll try to help.
My main response is that I am skeptical that you still have warts. When wart-like bumps persist for more than several months, and certainly when they do so for years, usually there is no longer an active HPV infection or actual warts, but scar tissue only. Since your warts apparently have been professionally diagnosed, perhaps that's exactly what you have. However, if you have not been evaluated by a highly experienced clinician in such matters, such as a dermatologist, that would be wise. Equally important, in this situation sometimes warts are actually precancerous lesions and should be diagnosed by biopsy.
Otherwise, I have no advice except to keep trying different treatments (freezing, cautery, podophyllin [or podofilox/Condylox], etc); sometimes warts respond just fine to alternating therapies. There is no immune boosting precedures that is know to help.
Best wishes and good luck with it -- HHH, MD
Thank you very much. Your response was very helpful.