I think of she's eating healthily, it sounds fine. My dniece was a large baby and toddler and my dsis was quite strict with her in terms of portion sizes and desserts/ crisps etc. She is allowed sometimes ie. Couple of times per week. Only drinks water. She is now 7 and very tall, pretty slim but still no ribs. I think if you're eating well you have nothing to worry about. If you're serving frozen meals, lots of crisps, sweets, mcdonalds, fruit juice, fizzy drinks etc (even one of those per day) you need to watch it a bit more.
And try not to worry too much about weight. Healthy diet & lifestyle is the key. Exercise (walking outside in the fresh air, go to the park, put music on & dance, for example), & a variety of fresh fruit, vegetables, different kinds of proteins, healthy fats, & complex carbohydrates. If possible, home cooked. Use as few convenience foods as possible, limit sweets, refined carbs (especially sugar), & unhealthy fats (generally animal fats). Try to limit foods whose ingredients you would struggle to pronounce or that has probably come from a factory instead of a field.