The 8th umbral calamity

[Iscah]

You could come up with any number of alternative explanations as to why she would be unsure, but it doesn't explain the earlier lines about a conjunction forming. There's a reason that I provided the direct quotes.

Again:

'Even bereft of guidance, you and your companions have accepted the burden of this star's troubled past. A conjunction has begun to form; an intertwining of your time and mine.'

'You may find your world to be very different. Or perhaps the erasure of our friends' memories has sown the seeds of a conjunction between us.'

"Sowing the seeds of a conjunction" can definitely be read to mean "erasing their memories means that the present situation is consistent with the future you told us about, so this might be the beginning of a time loop that connects up to your pre-existing future".

Then she appears to us on the ship. From her perspective the time loop has been slowly progressing all this time, and now at last it looks like she's reaching the conclusion of it, recognising the more recent waymarks of events that you must have described to her all those years ago. She's approaching the conjunction point where you depart this location on the timeline to visit Elpis and come back, completing the loop and ending that uncertain state where the loop could potentially fail somewhere along the way.

[Lyth]

...

I don't think that your explanation shows the reasoning behind those statements. A conjunction has begun to form. The erasure has sown the seeds of a conjunction. Look at the tense. These were not pre-existing; they were not predestined. That's why it's a bit more nuanced than a stable time loop, in which everything in-between the loop is predestined to occur.