Hey Growmie,
This happens sometimes, it's like the auto forgets it's an auto and grows like a photoperiod plant, I've had it happen to me a couple of times, the way you can get it to start budding is by changing the light cycle to 12/12 and after a week or so of that you'll notice it beginning to flower. Hopefully, I answered your question and remember ..."Happy Growing" and "Free your mind one puff at a time"
its size is due the 5 gallon pot its in. If you want a smaller plant, then put it in a smaller pot, 3 gallon would do. As for it not flowering, put in in 12/12, else it will keep growing