Start counting calories and start working out.
Also buy a food scale! $15 at target, measure everything you eat. After a while you will get a natural sense of how many calories are in what. Like 100calories for; a single slice of bread, 1oz of cheese, 1 apple, 1 banana etc..
I threw in a longer fast last week after a few people advised that and it seems to have worked to break my plateau, which I’m thrilled about!
But yeah, if anything I’d count calories for a little bit just to get a sense of things (like you said). And even some light activity is better than nothing, like walking is amazing if that’s possible for you.