I make my chicken broth from whole chickens or pieces. It depends on how much I want to make. The jello like consistency of cooled broth comes from the collagen found in the bones and connective tissue. I understand that you can increase the amount of collagen by adding the feet to the broth too. Apparently they contain a lot of connective tissue. Like you I will never buy commercial broth again.
If you want a quick test of your sensitivity to fructans try eating some Jerusalem artichokes and see how they affect you. They pass through me like grease lightining
-------------------- STABLE: ♂, IBS-D 50+ years - Science of IBS