Since you don't have a macro lens, if you're trying to get closer (your distance seems adequate already) it may be difficult to get the results you desire depending on how much detail you want to achieve without one.

Have you considered renting a macro lens?

I would stand with my back against a black backdrop if available, with nothing else to either side to prevent possible reflections in the eye. Other than that I think the photo you posted is great, just need to eliminate the light coming through the window.

This was a quick test I shot with my daughter when I received my 105mm f/2.8 Micro-Nikkor. Focus is sometimes tricky - I shot it handheld and I think I moved a smidge when I hit the shutter release.

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