To determine sex (or get buds), you must flower the plant, which means a strict light cycle of 12 hours on, 12 hours off.
No light whatsoever can get to the plant during lights out.
Within the 1st 2 weeks of 12/12, males will grow "balls" (pollen sacs), females will start to form buds during week 3.
What kind of light(s) do you have the plant under?