I assume you're using a parting tool? If so make sure you have the work positioned so you can sort of swing or turn your body as you work around a curve. If you rely on your wrists and arms to make the turns they will not be as smooth. If you are using the parting tool, are you pushing it by hand or "chasing" it like a graver with a mallet? I find that chasing gives better control.
It's easy to make little gouges; you don't need to buy them. Even assuming you don't have a forge. If you have a fine round file of the right diameter, you can file a groove in an annealed file, or piece of drill rod, or annealed masonry spike, shape the outside of your new gouge with files or a grinder, smooth it to 400 grit, harned using a propane torch, shine it, draw it to dark straw, sharpen it, fit a handle, and be ready to use it all within an hour. In an afternoon I can make a set of gouges all with different radius and have them razor sharp and ready to go. Take a few minutes to add some finish overnight and they will even look as good as they work.