Relax, Candi. You son is just being a toddler! From your description, he’s tall and lean and obviously growing. As for his diet, your WIC nutritionist is technically correct that it’s inadequate if her assessment is based on the standard WIC food intake form. However, there are other things to consider. For example, does he drink juice? Do you put tomatoes in the tacos or sauce on the spaghetti? If so, he’s also getting fruit and vegetable exchanges, although limited.
I don’t know if your husband’s work schedule is important here unless you tend to resort to convenience foods because they’re easier. When your son eats with your family, sit him and your nephew at a separate place, such as a child’s table, or make a “picnic” for them. Put age-appropriate fruits and vegetables in a bowl between them so that they can help themselves. Once you son sees his cousin eating all the food, he will probably reach in to make sure he gets some, too!
This is the secret to daycare facilities. Children will usually follow what others are doing rather than standing alone. I also recommend that you leave the boys alone and not offer something else if your son decides not to eat what has been set in front of him. Once he learns that alternatives are not available, he will start to eat other foods.
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.