How to not gain weight too much???

My pre-pregnancy weight is 58kg and I’m now at 29 weeks weighing 71kg. I was 62kg at my checkup on 2/12/22. My gynae has not made any comments about my weight gain and is telling me to eat more based on my baby’s estimated weight. But I’m already gaining so much???? Is there any reason why I’m gaining so much and how can I slow downnnn???