I have a very similar experience. I lost what was quite a lot of weight for me, around 7kg, by doing intermittent fasting after my son was born. Got down to 56kg, which I hadn't been since pre-kids, and it felt easy. I also felt like I was in such a deficit for ages, that I could almost eat what I wanted. I kept it off for quite a while, about two years, then it gradually crept back on.
Even though I've tried to return to strict IF, it doesn't seem to work now. I don't get hungry; it's almost as if I've trained my body not to need as much food. I'm still very low carb, and I rarely eat breakfast, but... have about 3kg to lose to return to my comfortable weight. It's not a big deal, so I haven't posted about it, but I don't feel as good in my clothes.
I've been doing weight training - and have been following quite a steady training schedule, but it still doesn't seem to have shifted my metabolism. It's kind of frustrating. I've started introducing more protein into my diet, and started eating breakfast again (usually just a small bowl of cottage cheese and some nuts), but so far (3 months in) I have only felt a little bit bigger rather than smaller. This seems a relatively common experience when starting weight training, but it's a bit depressing not to see any real improvements.
I'm of two minds. One of the tenets of IF (michael Mosely version) is that you really can't damage your metabolism as easily as people think. I do sometimes think...maybe I should just go stricter, be more patient, really calorie count, etc. But, I'm not sure I entirely trust this. I'm not sure - and haven't entirely ruled it out. But, to be honest, I'm sick of feeling weak, and the sense of diminishing horizons.
I think I'm going to push through and keep weight training - I imagine it might take up to a year to improve. So - basically, don't have much to add but you're not alone! And if anyone else has any advice, I'd also love to hear it.