Ay mamsh, 14 grams sa 16 weeks ay konti talaga, normally kasi ang babies ay dapat around 100+ grams na by that time, so I'd really suggest you check with your OB agad to make sure everything's okay with baby's development. A few of us sa mommy group namin had similar concerns before and it turned out important to monitor closely with the doctor, so don't worry but do get it checked ASAP para ma-rule out kung may any concerns!