I've not formally or intentionally IF'd yet, but I have skipped a meal here and there, because I simply didn't feel that hungry. I'm not convinced IF'ing should be done in a "white knuckle/ignore your body's pleas for food" kinda way. That seems like a body that isn't yet trusting that you'll feed it well overall.
Like you, I'm finding that some days I'm just not that hungry. I'm not tracking calories at all, my weight loss has completely stopped (at a place where I'm happy for it to stabilize)....I bet some days I take in only 1000 calories, another day I might take in 2000. I feel like I've reached an equilibrium where I can trust my body's signals (vs the days when I thought my body was saying "Must have milk chocolate").
Zone diet on and off for several years....worked, but too much focus on exact meal composition
Primal since July 2010...skinniest I've ever been and the least stressed about food