Definitely delay graduation. It will allow you many benefits
1. Applying as a US Senior = higher chance of matching
2. Applying as someone who has done research
3. Most importantly - it will allow you to do away rotations again because you can't really do those as a US grad.
It is a 'red flag' because you didnt match, but as long as you kill your aways and publish 10 papers during the year, no one will be able to say you didnt try hard. I know at least 3 people who didn't match, did a research year, did 3 more away rotations, and all 3 matched at one of their aways because of how hard they worked.
