Don't put a comma before the "if" in the last sentence: it should be "...but even if we caught a bus now, we..".
Actually the non-conditional form is probably more common: "if we catch a bus now, we will (still) be late".
The way you have it, it emphasizes the unlikelihood of catching a bus. With the present/future, you're expecting to catch a bus any moment, but are conceding that you'll be late either way.
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