The benefits of yogurt usually outweigh the negative aspects of the small amount of sugar and even dairy in non-sweetened organic Greek yogurt. Purchase an organic non-sweetened Greek yogurt which should contain no more than nine grams of sugar per serving.
If you make your own kefir, you can ferment it longer than normal thus reducing the sugar amount substantially because the longer it ferments the less sugar remains behind. This way, you can eat less yogurt and more kefir. You can also make homemade yogurt by the way.
If you would feel better about the yogurt, you could stop eating it for about a week to remove it all from your system. Then, start back with three bites the first and second day, and raise it slowing after that. I’d stay on just one serving a day eventually until another month or so on the diet.
If you believe that your treatment has been hampered in some way, you can describe exactly what you’re eating, including all condiments as well as the supplements your taking so that we can take a look.