@pop22 – the plant might have not developed very fast due to delicate source of light you have used (50W). Transplanting autoflowering plants is best avoided, in some occasions it might stun the growth and limit their final size.
Eventhough autoflowering strain contain the ruderalis genetics within the line to make them independent from the day lenght, it might happen that few seeds do not receive ruderalis genes in portion big enough to induce the autoflowering reaction. In theory the seed you had might also develop into what we could call "Fast Flowering" version of the strain, in this case it might require the switch do 12h day to induce the flower production. If that is the case the plant should finish the blooming cycle significantly faster. We encourage you to try to induce flowering in this plant by switching it to short day if it is possible for you. If this solution does is not working for you, we can offer you a replacement seed from the same strain to ensure you have one more attempt at this one.
As for feeding schedules and environment condition, we noticed a lot of people using some unorthodox setting which might also be the cause of stunned planned growth or even hermaphroditism
How many days has it passed since you switched the light for 12/12 ? sometimes the plants might not be physilogically mature to enter flowering, and will naturally remain in vegetation for as long is needs in some rare cases.