Weight Gain in Trimester 1

I am 1.58m, 43KG prepregnancy. Gained 17KG (40weeks). My tummy was small thou. Took 5 months to go back to 45KG but I don’t exercise so ya 😂 I read Google it says that the lower the BMI the more the weight gain compared to those with normal or overweight BMI. Not sure if it’s true anot tho. But just eat what you want, just go easy on the sugars (prevent GD).