I'm writing a poem, and like how it's flowing. But I find that a tiny pause shorter than a comma would do tremendous. Is there such a mark or multitude of symbols to make a short pause?
Depending on your poetic style, you can add a syllable to a word to increase the length of the sentence or line. However, it's poetry; that probably won't work. But because it's poetry, there's nothing against using two or more spaces after a word. The reader will automatically slow down if for nothing else because it's unusual.