Aiyoh, I feel you lah, a few of us mums also struggled with weight gain in pregnancy, it's actually pretty common! At 16 weeks maybe your body is just settling in still, some people don't gain much in first trimester, but since your nurse is watching it, better to chat with your doctor at the next checkup about whether you need extra calories or if something else is going on (metabolism, morning sickness still around, etc.). One of my mum friends found that adding protein-rich snacks like peanut butter, eggs, full-cream milk, or even a piece of roti with dhal helped more than just eating extra rice, and maybe try keeping a food diary to show the doc what you're actually consuming, sometimes we eat more than we realise! Hang in there, don't stress too much yet lah, but definitely mention it to your doctor so they can guide you properly.