There may have been Iron Lord previously unmentioned or rarely mentioned. Segoth, for instance. The artifacts Segoth's Head is the helmet of a Titan, embellished like Iron Banner gear. There's a quote from Skorri or Efrideet (I forget) that says that the Iron Lords ended up fighting each other at some point. Segoth may have been an Iron Lord, there could be others.

Segoth (I believe) was an iron wolf

Yet it has a quote from an Iron Lord in the artifact description. Maybe you're right though, and maybe fighting "each other" refers to fighting other Guardians instead of fighting amongst the Iron Lords.

I believe some of the wolves fell out with the lords

It might explain why there were 9 Iron Wolves that we know of and 10 Iron Lords. Segoth might be the 10th Wolf.