you cant go back (maybe you could but probably isnt worth it, would likely stress the plants a huge amount), just keep at 12-12. its not that bad, many people start at 12-12 intentionally to save time. the stretching could be either lack of light or just genetics, the strains you mentioned are sativa dominant so that could explain it although i have read that the strecthing occurs later on usually once switched to 12-12... but since its 12-12 from the start that might be why. if you need more lights cfl's are the cheapest in short term especially if you already have extension cords lying around but if they are around water IE you are spraying your plants with a mister instead of pouring water, they will die.
with a "random 150w bulb" I'm gonna step up and say you haven't got proper light and it's way to far from the plant. You describe your plant as stretching for light that it knows is there but hasn't found yet. Untill it has light that can actually produce growth, it's not going to grow. It will just continue stretching till it does. Move the light closer and bend the plant over and tie it down. As for the 12/12 from seed. That will reduce vegitave growth by having less time to grow and induce flowering as soon as possible, it's not going to ruin a plant though. It's more like a second rate alternative to growing autos. let it keep doing it's thing.
Your pics show some extreme stretching, I'm guessing the light is not strong enough for three plants and is way too far away. First thing you need to do is get that light closer, and get more of it. Might be able to prevent some stretching on the youngest one by transplanting, just an idea if it's possible. The other plants are stretched so far it might not be possible to LST them, but if it is it will help. Other than the stretching and slow growth they look okay though (Except for the crispy/curling leaves in the one picture) What are your temps?