Irregular AF and BFN testing?

Mary • TTC newbie, runner, and vegetarian with irregular cycles and period duration
I have an irregular AF cycle ranging from 32-77 days! For now I predict my AF to a window within the next three weeks. I believe I'm 15 dpo and have a BFN. When would you suggest I test again? I can't imagine being able to wait three more weeks for a possible AF. Thanks!