Ok. First go here and read everything so nect time your not at the mercy of everyones opinions about what is going on.
http://www.amsterdammarijuanaseedbank.com/Growguides/troubleshootingsolutions/marijuana-nutrient-disorders.html
Read it and memorize it! I would suggest writing it down or making a flow chart of the info so you truly learn it..and learn what each nutrient does! Ok back to your plant. It seems perfectly fine to me, it could be a little darker green (more N) but whatever. At two feet tall you can expect some leaves to fall off the bottom. They yellow, get lots of browning and then just fall off. You don't have a whole lot of light in there. I SCROG or veg heavily for 8-9 weeks under 600's and when flowering starts I loose allot of understory leaves.
A micro nute def would show more stark signs, typically on more than a single leaf. My suggestions:
Implement a foliar treatment plan. Foliar feeding allows for almost instant uptake of nutrients. One of the best all around foliar treatments is sea kelp. It has allot of micro nutrients (the cold pressed variety has much less) and more importantly it has a wealth of growth hormones in it that act to hasten the uptake and transformation of nutrients. There are a shit ton of different kinds. My favorite is sea green. It is NOT cheap ($60 a bottle) but it is the most concentrated stuff I have ever used 0.5ml/gallon for foliar application. So a small bottle will make almost 1,000 gallons. 500 if your watering with it.
My second suggestion is to top your plant. I would hack off the top 1/3. I top at least twice. Once at around 5 nodes and again at 7. You want to increase the number of main trunks as soon as possibly so they are as low as possible on the plant. Topping and LST are your friends. Especially if you only have one plant. A bushy plant with a nice even canopy will yield several times more than a single cola plant. This is especially the case running artificial light which rapidly decreases in intensity (the square of the distance)
Hope this helps