I think your chorus should rhyme. Choruses should be fun to sing, independently from their meaning, and that's where rhyme comes in. All you have to do is change the order of the lines. Depending on the melody, you can either keep or drop the "or two." If I was writing the melody, I'd keep it, stress the word "song" and sing "or two" as part of the next line, but a different melody might benefit from dropping it.

I'm keeping it cool
Singing a song, or two
Keeping it cool
Just Breezing along

Good luck with your show!

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