If you are overloaded with the work and feeling overwhelmed, there could be two reasons. Either you are actually overloaded, or you cannot manage your time, which is making you ineffective.
The solution is if you are consistently overloaded, ask for the support in the way needed. And be effective with your task management. See what you must do and what is most important, start from there. When the most important tasks are taken care of, you will feel more confident. If needed and if you can, move some work to your subordinates.
And if you feel such all the time, check if, apart from time management and being effective at work, if you really need an additional helping hand.