just so you know, a 10- to 20 lb rebound from your lowest weight is VERY common in year 3. I think it's just your body settling in to a weight it feels comfortable at - your new "set point". Of course, you can still lose again if you cut enough calories - but it could be a bit of a struggle if you're fighting against where your body wants to be. I've been dealing with the same thing since year 3 (and here I am in year seven...).
different things work for different people. I count calories, which my dietitian hates (she's into "intuitive eating"), but I'm obviously not cutting back enough or I'd be losing weight. It's tough... I know other vets who've done Weight Watchers, Keto, and/or intermittent fasting. Whatever works - some approaches are more effective than others, depending on the person.
to respond to your questions (sort of, anyway...), I don't do low carb - but the vast majority of my carbs are the healthy kind (fruit, veggies, whole grains). I have to average around 100 grams of protein a day because I malabsorb it (we discovered this pretty soon after my surgery), and I do manage to get that in every day. Other than protein, it's really just calories for me. If I stay in the 1500-1700 range, I can maintain my weight - but I'd really love to lose 10-15 lbs (!!)