I listen to a podcast called Intermittent Fasting Stories, where each episode is an interview with someone who’s been successful with IF. Most of them are in maintenance, all of them are still fasting but no longer losing weight (including the host, who lost 80 lbs and has kept it off for seven years, including going through menopause.).
It does seem, listening to these stories, that IF is not like a continuous weight-loss machine; at some point you stop losing weight but maintain the loss.
I (M / 33 / SW = 213 lb / CW = 139 lb / height = 5 ft 10 in) haven’t been on this journey nearly as long as you but am kinda-sorta able to maintain on OMAD after 10~12 months of loss (currently 16 months in). I guesstimate my effective TDEE to be just slightly, maybe 100~200 kcal/day higher than the Mifflin - St Jeor formula predicts for my sedentary stats (activity factor = 1.2). This doesn’t necessarily imply that I’m a (mildly) lucky outlier actually expending more – it could be entirely or partly a consequence of OMAD and/or eating for the most part whole foods “stealing” a slight chunk of my intake. Regardless I never had to explicitly calorie-count on that dietary constellation, just always ate to comfortable satiety while steering clear of food choices that would give me a hard time moderating (fruit juices were a particularly nasty example).
Currently my maintenance workflow is as follows: Is my 30-day scale weight moving average threatening to exceed maintenance weight + 4 lb? Restrict – leave that extra slice of bread be, don’t attend a third restaurant dinner in the same week, keep it at two servings of pasta instead of three, …). Is the moving average threatening to fall under maintenance - 4 lb? Augment (more butter or oil, third serving of pasta, extra nuts or dairy, more / unbounded social meals, …). The latter also applies when my energy levels are crappy or when I expect a particularly active day (contemplating preemptively switching to TMAD on such occasions).