I've never heard of the name Zenzele, nor have I read about it anywhere. As of right now, it looks made up to me. I don't find it feminine either, sorry.
Just because you're not of African descent, doesn't mean you can't use it (or a Russian name, etc.). If we only used names that corresponded with our ethnicity, we would live in a very boring world, I think. So, I would say not to let that change your mind. My motto: nothing should stop you from using the name you love.
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Lissa Hannah-
As soon as tradition has come to be recognized as tradition, it is dead. - Allan Bloom