It's really a lot of trial and error to find a toothbrush and toothpaste that you can tolerate. I recently had to swap toothbrushes because the product I had been using for years was redesigned, and the new version was difficult for me to use. Likewise with toothpaste I had to go through a few options before I found one I was happy with.
And brushing with water is better than not at all! ποΈ
As for how clean the bristles are, make sure you toothbrush can dry out properly after brushing. I always rinse mine before and after, and monitor for any mould at the base of the bristles. Generally it's recommended to replace your toothbrush every 3 months regardless of its condition.