I've had 10 to 15 hives for the last 6 years. I seems like every year at this time about half my hives are doing great and are ready or about ready for honey supers. About half are not doing nearly as well. Of those not building up, about half will build up well in another month to produce honey and the other half never do. They are not the same hives from year to year. Is there a way to tell which of the current poorer ones will or will not produce? If there is, I could combine, requeen, etc. I don't mark my queens.
Try equalizing the strong hgives and giving to weak hives. If the hive continues to struggle, combine or re-queen.
I'm assuming that in NC they would have had some nectar flow by now? Hen bit and the early fruit trees etc? I would think it would be a good time to asses them. I don't look so much for how big they are as how well they are growing for how big they are. A small hive (coming out of winter on a small cluster) can only raise so much brood. If they are doing what I would expect them to be able to do, I'd leave them alone. If they are dwindling, I'd requeen or dequeen and combine.