Another question, what wattage should I use for the fluorescent bulb? The bulb I am using now is 6500k, is that good?
The 6500K number isn't the wattage, it's the "color temperature". A higher number indicates a light closer to the blue end of the spectrum. Blue-green light is good for green, leafy growth phase of plants, but if you want it to produce blossoms and fruit, you'll want a light that's more toward the orange-red end of the spectrum, which means a lower number. Look for a bulb in the 2500K-2700K range or labelled "warm".
As for wattage, you'll probably want the brightest you can find. It takes a lot of energy to make fruit.
I agree with the others who suggested overwatering as a possible problem, too. Citrus like to dry out a bit between waterings. My citrus trees always seem happiest if I let the soil almost completely dry out once in a while.
Also, I can't tell from the picture, but check the tape holding the trunk to the metal stake, and make sure it's not constricting the stem at all. If it's been on there for a while, the trunk can grow and get pinched by the tape. If it's tight, take it off and either get rid of the stake or re-attach it loosely with some velcro or something.