The tree is about 48 inches tall, graft is 9 inches above soil line, stake is banded to the root stock 6 inches from the soil line.

I can see there are suckers just sprouting from the root stock below the graft.

When it comes to watering I am careful to water at least every two weeks with 14L of rain water or every week with 7L (1 watering can full).

If the problem is that the graft was not successful is there anything I can do for this tree?

I've had it at least 3 years now, I think it might now be the 4th. Wouldn't it have done anything by now? The apple I planted at the same time is doing fine and is over 2m now with a trunk that is getting thicker. The cherry looks almost the same as when it went in.