I've achromatopsia, which chromosome is affected?

Several. Rod monochromatism is most common form of achromatopsia, inherited as autosomal recessive condition; it can be can be caused by more than one gene mutation. So far, mutations or variants of any of 4 genes, cnga3, cngb3, gnat2 and recently pde6c, have been linked to each causing rod monochromatism. These 4 genes appear to account for about 79% of cases of rod monochromatism. See comment below—>.