So about the Rey being a Jedi thing? Well...it really depends on what Rise of Skywalker brings to the table with regards to Rey's character.
Sure, Rey has been fighting the bad guys and using Force powers, so one could try to argue that she is a Jedi because she's doing what Jedi do: fight the Dark side of the Force. but that is not what truly makes a Jedi. it is not enough to fight the bad guys, it is not enough to wield a lightsaber, it is not enough to be able to use the Force. What makes a Jedi...well a jedi, is being able to overcome themselves, and grow from it.
Luke became a jedi not because he defeated Vader, but because he defeated himself. confusing, I know, so let me explain. On Dagobah, Luke fails the test of the cave, which wasn't a battle against Vader, it was a battle against the darkness within himself. He gave in to his fear and anger, and struck Vader down. Who turned out to be him. It was showing that if Luke did not overcome the temptation of the Dark Side of the Force, he could become the very thing he sought to destroy. A fact hammered home by the throne room fight in Return of the Jedi. Luke gives in to his anger and defeats Vader, but then realizes that he is becoming Vader in the process. When he refuses to strike down his father, when he steps away from the anger and hatred he had for the man who killed his mentor, killed his friend, who wounded him on Bespin, he proved he was able to overcome the darkness within him, the temptation, and thus became a Jedi Knight. He, in essence, 'defeated' the darkness within him. This is what made Luke a Jedi Knight.
The Jedi of the Prequel trilogy, though it was never shown in the movies, did the same thing. Padawans faced trials that would expose them to the darkness within themselves, and if they could overcome it, they would prove they're ready to be Jedi Knights.
So far, Rey has never had that problem. She has remained pretty much incorruptible, and has not ever had a moment of darkness or temptation. The closest we get is the whole business with her parents, trying to find out who they are, but even that isn't really something that works as 'overcoming the darkness'. That scene in the water cave in The last Jedi is probably trying to convey some type of message and be a similar experience for Rey that the cave on Dagobah was to Luke, but it isn't being the RIGHT one for someone who is trying to be a Jedi Knight. Rise of Skywalker MIGHT try to give us a scene like that, where Rey is tempted by the dark side of the Force, and that at least would be the right path towards her becoming a Jedi. But given the character so far, this incorruptible source of good that she is, it would feel fake. Luke became a Jedi because he legitimately COULD fail. Because even with his training and development, he was still flawed, and he needed to overcome that flaw to be a Jedi. Rey just has not shown that to us at all so far. And even if Rise of Skywalker adds in a scene like that, of her overcoming darkness within her, it just wouldn't feel realistic or right simply because so far she has never shown that her falling to the dark Side was a possibility or even a danger. *shrugs* That's just my take on it, but I do think that Rey can't really ever be a true Jedi simply because a Jedi isn't simply a 'good guy warrior'. A Jedi is someone who has faced the darkness within themselves and overcome it, making them stronger for it.