It is easy to be indirect with parents, given all the emotional complexities involved. Sometimes a person will even think, “She is my mom. She should know I need this without my being blunt about it.” But if what you have said is not getting through, you have to be direct and clear, though not mean.
Confront your mother from a stance of being an adult, rather than from a position as being her child. The basic difference is to make your discussion more about the relationship and less about your needs.