I don’t think 18kg in 6 months of low carb is unexpected or excessive, assuming you had it to lose in the first place. It’s roughly 1.5lbs a week. Just about what’s officially recommended. Might sound a lot as a total because using the high carb low fat methods people don’t sustain that for 6 months cos they’re hungry or feeling lousy
People get used to seeing you a certain way, they are jealous, they mean it as a compliment even though it sounds like an insult. Ultimately it’s none of their business.
A lot of us find we naturally hit a weight our body likes to maintain assuming a similar eating plan. If we’re happy with that great. If not it’s about tweaking the fat and protein, assuming your carb level is working for you. More to slow or reverse weight loss, less carbs or fats to encourage a bit more loss.