I like your painting it's the general impression created by toned colours, balanced composition and serenity of the theme. Beautifully done - I don't know why but I connot take my eyes off the wall in the background
regarding photo itself usually I have this ugly light effect as well but this time I tried to get rid of it somehow. I put the painting so that it was lit from one side by room windows. The weather was cloudy so this light wasn't very intensive. And I even turned the painting a bit away from window, away from straight light, getting overall room ambient light to be the main light source. I think that was the main point. If your source light isn't too intensive and it's more ambient than a point-kind then it should help.