You come across multiple instances of "true souls" not have turned into mindflayers before you ever even get to Halsin. The game has already given you multiple clue that the tad pole in your head, is not "normal" as to what Lae'zael and the others know to be true of illithid tadpoles, that fact is what relieves the pressure that is conveyed in the very beginning. It's further corroborated and reinforced if you do Omeluum's quest.
You seem to be playing the game without paying any attention to the contextual clues that the narrator and the NPC's are giving you from the moment you meet Astarion going forward. I don't think I can help you with that. Maybe that's a failure on Larian's part that they didn't envision a portion of players wouldn't pick up on what they were trying to convey.
I picked up exactly on the contextual clues, which stated the process has been merely *SLOWED*, not *SOLVED* and that you can still turn *ANY MOMENT NOW*, because you are already past the standard deadline. Saying that your situation is weird because you should have turned already in no way implies you aren't about to turn now. It just implies it took longer than usual, not that it isn't happening, and not that it isn't about to happen.
If you could find a true soul that's verifiably been infected for months on end already, that would be one thing. But you don't. Every true soul, be they companion, dead when you found them, or killed by you, can only be verifiably infected for the same length of time you were. Even with Gut, you know she was already there before you, and not on the mindflayer ship, but you have no way of knowing if she was infected the day before you, the week, or what, so you can only treat it as her having been infected the same instant as you. So they are all just as liable to turn overnight as you are.
The first, and only, contextual clue that you don't need to be worried is Omeluum. And you don't even need to do his quest by the way, in the very first conversation he tells you about the stasis. If you let him brain scan you at least. You, Grudgebearer, have been picking up on something they DIDN'T convey. Omeluum presents the first and only reasoning for thinking the way you are. Again, saying the process is slowed means absolutely nothing. It has no significance. Only saying it has been stopped entirely, i.e. Omeluum telling you about the stasis, has any significance whatsoever. Your doctor telling you the rate of your cancer's growth has slowed is an absolutely worthless statement which has no effect on what you should be doing, until the doctor can say it's cured. To treat anything before Omeluum as anything other than this is patent stupidity. If one wants to roleplay as such that's a-ok, but they should give that character the lowest rollable intelligence of 3, which we can't even do since the game uses point buy.
And where did I say that it solved the problem? Nowhere.
What I've said, is exactly what the game tells you as you progress through it, that what you though was the case with the tadpole in your head, is not, that you are not in imminent danger of succumbing to ceramorphosis, which is why as you play the game, the early sense of "OMG WE HAVE TO GE THIS OUT ASAP" lessens, as you learn more information.
