To veg or not to veg?

Send it into flowering, it's time, 4 months is actually 3.5 months too long in the vegetative phase, and even after 4 months, they don't look like they should for that period. I think you've stressed the plant too often, causing it to have growth setbacks repeatedly. I would send it into flowering now and not touch it anymore to avoid further delays. What's important is especially the pot being used; they look healthy overall, but for 4 months, they're still very small... feel free to check out my grow, I kept mine in VEG for about 3 months, with 1.5 months in a 1L pot, so I had even worse conditions than you, yet they still grew as they should... Could it be that your pots are too small? (the more rootless, the greater the nutrient uptake and thus the growth of the plant...)