Ferts could be affecting flowering. Withholding nitrogen is part of force-flowering. So go for a fert with a low 1st number.
Light cycle- if you've got leaks, you've got problems.
Maturity- If plants aren't sexually mature alternating nodes they will take longer to show.
Timing- males tend to show towards the end of the first week, females a little after. So you could look on it as a good sign that you haven't found any males yet.