Children have more weight gain in the first 12 months than almost any other time in their lives, tripling their weight from birth to the first birthday. The fact that your daughter is growing in length shows that she is still thriving, and you have probably noticed that she is looking slimmer but taller. Toddlers are certainly more active but have lower calorie needs than they did as infants and tend to snack their way through the day rather than sit for meals.
Your concerns are very common for new parents, and I would be careful not to start overfeeding her just to add pounds. Make sure you offer nutrient-balanced meals and snacks with lots of fruits, not just juice, soft vegetables and whole grains, like whole grain crackers and bread, as well as high-protein foods like cheese and yogurt. Be aware that children this age often refuse to eat meat.
Please look at our Child Feeding Series in the articles section of this website for more guidance on feeding young toddlers.
Our parenting advice is given as suggestions only. We recommend you also consult your healthcare provider, and urge you to contact them immediately if your question is urgent or about a medical condition.