Are womans breasts supposed to be kind of hard but firm?

Yes and no. Breasts are composed of glandular tissue (usually firm) but contained within a fatty matrix (soft). Depending on the relative density of the breast parenchyma relative to the distribution/volume of fat, the breasts can greatly vary in consistency from firm to soft. However this should be relatively symmetric, consistent and homogenous throughout the breasts. Localized firmness requires evaluation.