My son has low hemoglobin...advice?

Ww just came from the docs. My baby needed his 12 months blood work for hemoglobin and lead. He has low hemoglobin. They are sending us iron drops. However the bigger issue here is im sure he has low iron due to not eating. He throws up most of the foods i offee or just gaggs. The doctor claim this is all normal. I want to try different ways of introducing veggies especially for his iron and solids. He hates potatoes even diced up! Any ideas or suggestions are welcomed