Hi Andy, I don't know much about Nikon, but maybe you can try a 24mm prime which is so light and small that it should be good for candid photographing. A decent DC with 28mm wide angle should be another solution. Happy shooting, waiting to see more of your works.
I love your pictures. Specially the daily life in Ukraine, i think they are very valuable. Did you use wide angel lenses in street photographing, i think it is worth trying.