In my group people grabs their tasks from the backlog. The process is:
- There is a pool of tasks that this sprint should finish
- A team member grabs a task from the pool
- After the task is done, check in code, send an email to team, as for code review
- While waiting for code review response(s), grab another task
It could be true that your manager doesn't like you, but I would suggest you do your best to change your image. This will also help in your next position if you do need to find a new job