I should start by saying I'm in the high BMI category and had a BMI of 35 when I got pregnant, so the guidance is to put on between 11 and 25 lbs total. I'm now 24 weeks and have only gained 3.5lbs despite having a big bump and needing maternity trousers. I had a scan at 22 weeks and the baby is measuring fine, I'm just worried that it seems to not be very much and the calculators all say I should have put on about 7-8lbs by now.