How to make my slapshot go higher?

How can i make my slapshot go higher? Like i flex my stick 1 inch before the puck, and i can't get it top shelf. How do u take a slapshot anyways, i just bring back my arms, slap the puck and swing my stick as hard as i can to the ice, and flex, and shoot, but my shot wont go that high. i ALSO follow through. how do u do it? P.S. i have an bauer x60 hockey stick with a pm9 st.louis curve