What is correct in this situation?

You answered correctly. In this situation, you are approaching an intersection with a yellow diamond sign, which means you are on the priority road. The motorbike is coming from a side road and must yield to traffic on the priority road. That’s why you have the right of way, and the correct action is to allow yourself to proceed first. You do not need to signal a left turn here unless you are actually turning. Remember: vehicles on the priority road always have the right of way at such intersections. This helps prevent confusion and accidents at intersections without traffic lights.