I certainly hold to the theory that Rey's memories have been altered in some way.
I also thought back when I first saw TFA that it was Kylo Ren that dropped her off on Jakku. The way he calls her a ”Scavenger," and the way he freaks out when his subordinate mentions ”the girl," after the Falcon escapes Jakku makes me think he knows more about Rey than she does. I also like that Kylo mentions the island when he's probing her mind. She's already seen the future and doesn't seem to recognize it. I thought that maybe during the early years, before he destroys the academy, Rey was a very gifted student at the Jedi academy. Ben gets corrupted by Snoke, who orders him to wipe out the academy, but he can't bring himself to kill this little girl that he views as a sister, (his constant struggle with the light making him momentarily weak), and he takes her away to Jakku, uses his mind tricks to block her memories, and went back to Snoke like, ”yeah, I took care of the academy! You don't have to verify that!"
But on another angle:
The meaningful looks that Han gives Rey, especially the kind of sad look he gives her as they land at Maz's temple when she says she's never seen that much green before. It's like he feels bad, but for a deeper reason than just her seeing green for the first time. I got the impression that he and Leia know more about Rey than they let on. The cut away after Maz asks Han who Rey is seems also very telling. I feel like if it was nothing, they'd have just continued with Han saying something like, ”I don't know," or ”Just some stray I picked up on Jakku," or anything. It felt like a deliberate omission.
I also think they filmed more of the Rey being left on Jakku flashback than what they showed in TFA. Probably so they can use the same little girl for any future extensions of that scene. The way Rey reacted to seeing little Rey begging for whoever left her to come back made me think that it was a new memory for her too. Like she hasn't seen it before either. Perhaps it was a blocked one that became unblocked when she touched the child killer, uh, I mean Luke's lightsaber.
While I'm not so hung up on who Rey is as I was back when TFA came out, I can't help but feel that there were deliberate omissions that they'll address in the next two movies. Chances are answering those questions while TFA was already struggling to establish the new status quo of the post RotJ Star Wars universe, would just lead to more questions that the movie didn't have the room to answer. I think TLJ is going to be quite a character piece, and was always going to be.