Juga, look at the last 500 images you've taken, and of the ones that didn't work, figure out whether it was due to technical or other reasons. If technical, was it due to not enough light, blur due to movement, lack of image sharpness, lack of reach, lack of breadth? Which of those shots would you really, really have wanted to get? Depending on what you find, you will see whether you need more light, better lenses, or a better body. We all have our biases and our own experience informs our advice to you, but it may not be relevant. What you have to figure out is what is your most common limitation that is preventing you from getting the majority of the not-so-great shots. Once you have that answer, you will have a clearer idea of where you need to spend time/money/effort.