Then why do you disagree with the term "works-based" salvation? I know you give some credit to God for playing a part, but as you said, He is done. Therefore, again as you said, whether one goes to Heaven is "BASED ON" if he does enough works. That is works-based salvation.
We believe that freely undertaken works of love are necessary for our finlal justification, but we also know that these works have that effect solely because of the sacrifice of Christ. "Works-based salvation" would imply that we earn our salvation independently of Christ through overall acts of righteousness. This might be what some (pelagian) Christians believe, but it is not the Catholic belief.