Worried i am not producing enough milk?

My Daughter is 3months old and does not seem to be satisfied through out the day and does not sleep much through the day and seems to always be hungry. The only thing is she is already sleeping 12 hours through the night without even feeding so that makes me think that she must be satisfied. Its just confusing, has anyone else experienced this? Im not complaining because she is very good at night just wondering why the day time she seems so unsettled?