Can a runner "forfeit" forward progress?

1. My understanding is: If the referee has determined that the runner's forward progress has been stopped, the referee will blow the whistle to end the play.

2. Once the whistle has blown the play dead, the attempt to run in circles to try and get more yards won't matter, because the play is already over.

3. If the referee had not made the determination that the runner's forward progress had been stopped, then the runner does not get the benefit of forward progress.

4. If the referee had not made the determination that the runner's forward progress had been stopped, the runner can lose or gain yardage afterward.

5. This is my understanding of that rule.