Agree with Kriori that you need to upgrade the photographer, not the equipment. Once you know more, then you'll have a better handle on what equipment you need/want. I know as my head has filled with information, the way I shoot, what I shoot and the equipment that I choose has changed.
Recently (a trip to China and several trips to Tokyo), my kit consisted of D700 + 24mm f1.4 + 50mm f1.4 + 135mm DC f2 with an S90 in my pocket. I probably get considerably more dust on my sensor, but I love my primes. That being said, I did just pick up the 24-70mm f2.8 the day before yesterday. Figured I might use it more as my travel lens. It's not always easy to carry around a load of lenses when abroad.
Since you're a Nikon user, you might want to check out bythom.com. Some good informative articles there. And I think Thom generally pushes the "it's not the equipment" line to his audience.
Also, regarding your flash, check out Strobist.com if you haven't already.
Oh, regarding your 700 shots... you haven't even warmed that camera up yet. I agree that I could burn that off in two days. Having said that, shooting more doesn't mean better shots- generally a lot more throw-aways. However, when you're trying to beat down the learning curve, I think shooting a lot (while paying attention to the settings you're using/changing) is a positive thing. Later on down the road, once you're comfortable with where you're at, you can cut down the frequency again (say to a film-shooter's level).