Within the Scrum framework, you are a member of the Scrum Team (which includes the Scrum Master and the Product Owner), and also a member of the Development Team that forms a third of the Scrum triumvirate. You have no other title within the framework, and the distinctions you are making are invalid within the team-oriented structure of Scrum. Extreme Programming also uses a team-based approach, although it is actually a set of practices rather than a complete project management framework like Scrum.
You are likely to get a different answer on Workplace SE or Programmers. Here on PMSE, though, you'll get the project management perspective. From the agile PM perspective, your role should not have the boundaries you are attempting to layer on it.
Your Team Isn't a Scrum Team
Your team is probably not a Scrum team. Such a team would be self-organizing, and would have a Scrum Master and a Product Owner. While Scrum Teams exist within larger organizations, and may have people on the team who report to line managers like an "App Development Manager," neither the project nor the team would be run by someone in that role.
Additionally, Scrum and XP teams are cross-functional. Ideally, that means that everyone shares responsibility for all aspects of the product. While Scrum and XP teams can and do divvy up work within an iteration, the team as a whole collectively owns all the work and is often required to swarm over particular stories as a group. The fact that you have eight developers responsible for different things, as well as a manager and a team lead, means that:
- The team is likely to be assigned work rather than self-organizing to get work done.
- Team members aren't working on things cohesively because work is partitioned.
- Team members are being held individually accountable for deliverables, rather than being responsible for them as a team.
The fact that you have a separate "team lead" role also means that you have an internal hierarchy which is antithetical to the concept of a cross-functional, self-organizing team. Whatever else your team is or isn't, it isn't Scrum and it probably isn't agile.
Clarifying Your Role
Since your team isn't following a standard agile framework, you will probably want to clarify the scope of your role and your individual responsibilities with the person you are actually reporting to. In a command-and-control framework, that will be your project manager or line manager—and in some cases, both—rather than making assumptions or asking your teammates.