solids!

So my LO has been eating solids for awhile now and today we were at an appointment early in the morning and so she skipped her usual time she gets baby food. All I brought was formula like I always do when we go out and she drank 8oz and wanted to drink even more. We got home and I put her in her high chair, brought out the baby food and she got so excited and acted like she was starving. That's never happened before though until now, I thought formula filled them up and was their main source of food??