I'm getting a bigger box (about 5ft tall) so i will have plenty of room to grow this little gem. I don't want to restrict the plant as adding a shallower plant pot with a wider diameter can only go so far in a small box. I think the solution is simply to get a bigger box which is what i have done.

Hopefully if it arrives tomorrow then i can re-pot my plant and also do some other changes such as change the light bulb to a bigger one with a higher wattage (325 watts with a Colour Temperature of 6500K) until its time for flowering, then i will consider switching the bulb to a warm white or soft white bulb with a colour temperature of 2700k (because thats what i reas is best for flowering) not sure what the best wattage for flowering a single plant with a single bulb is though.

Need to think about a reflective material for inside of the box (all i have is tin foil so i may have to spend some more cash on a better alternative)

Got a Ph tester in the mail also seeing as my plants lower leaves are turning yellow and dying. (Im guessing its the nutrient issue mentioned at the top of this thread)