I'm not sure what the next step is?

What should I do. I'm an aspiring photographer and I have a Nikon D3100 and a 18-55 and a 55-200 mm lens. Should I move up to a better camera or keep investing in lens?

I have two thoughts on that…

1) Photography is roughly 70% photographer skill/experience, 20% lens quality, and 10% camera body
2) I would rather have a $600 camera with a $1, 500 lens than I would a $1, 800 camera and a $300 lens

Unless YOU can list specific reasons why a new body is needed, I would continue upgrading the lenses. I upgraded most of my lenses from f/3.5-5.6 to f/2.8 or better before I finally bought a new body.

I could give you valid advice like "tell us what your gear isn't doing". I could tell you to spend some money on training but that doesn't get anyone a best answer.So…

Get the 16-85, I own one, it's great!1

If you can tell exactly what you are missing from your camera or lenses then you should know what your next step is. All dSLR's are basically the same. They generally differ in range of controls and ease of access to those controls. Lenses vary by angles of view. It is possible for even a seasoned pro to survive with your equipment (and possibly with just the addition of an external flash and maybe even without the 55-200mm) for the rest of his life or his gear whichever comes first as long as he knows exactly what he's doing. Recalibrate your wants and rechannel to your needs.