Why are my plant at different stages of flowering ...

A few things to consider: (1) If your temperatures are below 23°C (73F) the growth rate of the plants is considerable slower than if it were on the ideal temperatures. (2) Checking you first four weeks, I could see that you had a low temperature issue, that resulted in slow growth. (3) Contrary to popular belief, autos don't start flowering according to age (number of weeks), they do so when they reach a certain development stage, this been the 5th pair of leaves fully opening (sometimes the 6th). Checking your earlier pictures, what you experienced was not a faulty autoflowering seed, it was a problem of low temperatures that retarded the sexual maturity of your plants. Once each plant reached that stage they started flowering, regardless of the light schedule. Mastering the ambient (temps and humidity) is more important than anything else you might do.