If you do actually need your medications to not have specific things in them, I would think your insurance would approve compounding with a letter from your physician verifying this need. It may take awhile to get approval, but would be worth checking into.
Also, you could call the insurance company and have THEM find you a list of manufacturers that provide acceptable versions of each medication you take (most, if not all, insurance companies employ pharmacists to do various things, such as this).
OR, find a different pharmacy to go to. Chains typically don't want (or don't have staff) to put in the time for one patient with very specific needs like this. Find a smaller, non-chain pharmacy (if possible), and you might get different results.
Source: I am a pharmacist. When I was a student, I did a rotation at a mail order pharmacy, and a patient had sent a message in requesting they fill their prescriptions with "gluten free" medications. So that was my project, to find acceptable medications. I had go through all the manufacturers this mail order pharmacy possibly carried, contact the manufacturer, and compile a list. It took a long time, mostly to hear back from the manufacturers (they didn't always have a list of gluten-free meds readily available). But it has been a few years, and these kinds of allergies are popping up all over the place, so manufacturers may be more prepared to supply that information.