With a 75 watt LED, growth is not going to be phenomenal and switching to 12/12 and starting flowering will take a while due to the limited amount of light not supporting any sort of rapid photosynthesis or plant metabolism.
Hang in there, flowering will happen eventually, but in reality, don't expect any rapid progression, 75 watts is barely enough light to keep the plant growing. Cannabis is "designed" to grow in bright sunshine, a 75 watt LED is vastly different to bright sunshine!
Just be careful with "bag seeds" too, most are the result of hermaphroditic plants and will carry dominant genes for being hermies themselves.
Buying feminized seeds from a reputable breeder (Sweet Seeds are awesome!) will be a lot cheaper than spending months growing a hermaphrodite or male plant, by saving a few dollars and risking your grow with "bag seed". "Bag seeds" may be fine for experimenting with, but really should not be the only option for your main grow in my opinion.
Hope this helps, Organoman.