Pregnancy weight gain

I was devastated when the last check up showed that I gained another 4kg/month. It has been the 2nd time consecutively. I only ate the usual portion except for the extra ice-cream I took after dinner :p Well, my tummy is still as small as ever compare to my tremendous weight gain. To date (@week 28), I've gained a total of 12kg. Honestly, I think the extra 2kg was from the unnoticed weight lost I had when I first realised I was preggy. I mean...all along my weight was yoyo-ing around 54-55kg. But the first time I weight myself at the hospital, I was 53kg (the weight I was in when I prepared for my wedding - read: lightest). So I'm suspecting that actually I only gained 10kg, which was more comforting...hehe

I stumbled upon the weight gain calculator from http://www.babycenter.ca/ just a moment ago. After keying in all my height and weight, this is the estimation I get.

How soothing to know this 'fact'. But then...why do doctors or nurses in gov clinic be so alarmed when I gain that much?? I still have a buffer of say...5kg for the next 12 weeks..