weight gain

Cl

Hi all I am almost 15 weeks and still haven't gained any weight. I am not over weight I'm 5'6 118lbs and this is my first pregnancy reaching the second trimester. I exercise 3-4 times a week a mix of cardio and weights but nothing intense. Anyone else out there not gain weight until later that is in their normal weight range when they got pregnant? I wasn't concerned but my husband keeps on asking why I'm not gaining weight!