Bowl turning.......there are as many opinions, as there are those who make bowls......and, you know what they say: "Opinions are like xxxholes.....everyone has one!
Keep in mind that the larger the shaft diameter of the gouge, the heavier it will be. The heavier it is, the more stable it will be. A newbie turner will tend to have the "death grip" on his/her tools.....and, in a way......that tends to stabilize the tool, but prevents you from having a smooth flowing transition through a curve. So.......as your knowledge and confidence increases, your grip becomes more relaxed, which allows that smooth transition of the tool over the tool rest. A light grip, with a heavy tool is optimum, but sometimes the grind shape of the smaller tool is better for some applications.
As for bowl gouges, I tend to think the minimum would be three of them......1/4", 3/8", and 1/2". (This is the English measurement, so the shaft diameter is actually 1/8" larger than the designation.)
Another "mandatory" tool for bowl turning would be a scraper. A new turner could get by with one round nose scraper. That way he could scrape left and right, and plunge straight in with the base flat to the tool rest. In addition to that, he could shear scrape left and right with a single round nose scraper. Ideally, though......quite a few scrapers will serve all the needs a bit better, if the grind is specific to the task.......soooooo, a variety of scrapers will eventually be in the tool bag of the more advanced bowl turner......
John......go ahead and give bowl turning a try with your single bowl gouge. It can be done with great success........but, you will quickly be thinking of buying a variety of different tools in short order! Some will become your favorites, and you are the only one who will ultimately decide what your best tools are!
-----odie-----