Multiple team members on a project with different roles

I have yet to figure out a solution to our dilemma. We have projects. We have team members. Depending on the project, members will have a different kind of role. For example, User 1 will be a team member on 3 projects, a mentor on 1 project, and a supervisor on another. Each project will have multiple team members in their different roles. Each team member needs to have access to a project they are assigned to, but cannot have access to a project they are not assigned to. Only a supervisor or administrator can assign members to projects (that's easy by role because the roles are the same regardless of project).

My relationship structure is projects has many project assignments ( Fields: member = user, role = text-multiple choice, related project ), I can run a report that restricts the project assignments to current user, but when you run that report, it opens up the project assignment not the project. I can't run a report for projects assigned to the current user because the project assignments are children of the project and only summary fields are available. HELP!