First iui

Hi! I did my first iui on the 1st of july. I'm now 14 DPO and have tested every morning for the past few days and have gotten BFN every time. Yesterday I started using the restroom way more often than normal and wondering if it's still possible to get a positive? My next cycle is suppose to start in 3 days. Should I wait until expected period or was the 14 days long enough to wait for an accurate reading?