Around the 7th month (28-32 weeks) babies are still pretty tiny compared to full term. My first was estimated around 1.1–1.3 kg at 30 weeks, some friends had babies closer to 1.5 kg at that point. The growth really speeds up in the last few weeks, so don't stress if your ultrasound shows on the lighter or heavier side. Every baby grows at its own pace and those weight estimates can be off by a few hundred grams anyway. Just focus on eating well and staying hydrated, and trust that your little one will keep packing on weight in the home stretch.