Weight gain

I started off my pregnancy normal weight I believe me BMI was 23. I am now 18 weeks pregnant and I gained 9lbs (since the day I missed my period at 4 weeks pregnant, not since my first prenatal appt at 8 weeks). My doctor said that was a lot and to slow down. I’m confused bc I feel like that’s not a lot unless you start pregnancy being overweight. By the time I was 18 weeks with my son I had gained like 15 or maybe even more.

Maybe she thinks I gained 9lbs just in the 2nd trimester or since my first prenatal appt at 8 weeks. There’s like 10 different doctors in the OB office I go to, and she’s the only one who has said that