I'm not trying to change your mind on how you scored because having watched some of the rounds again I can see the arguments from both sides. To get a 9-3 you've only given AJ the rounds that you had to though, so it's minimum rather than maximum. After this explanation, if you still can't see what I'm saying we are best off agreeing to disagree though.
I can see why you think it might have been unfair to have it even after the 8th because in all fairness rounds 1 and 3 and 7 were stronger-more dominant than any round AJ had in those first 8 rounds. That's not really relevant though, each round starts with a clean slate. You yourself gave AJ 3 rounds in those rounds(were they 5,6 and 8 out of interest?), giving a score of 5-3 after the 8th, which means you're really arguing over 1 round and there were 2 swing rounds in there, whether you identified them at the time or not.
More people seem to have scored the 2nd round for AJ than they did the 4th between the two swing rounds, from the boxing fan scorecards I've looked at. In the first half of the round, AJ landed the better shots, even though Usyk was displaying the better ringmanship and defence, AJ still got some good shots in((landed to the body and head forcing Usyk on more than one occassion). I actually think Usyk felt those punches(especially the body shots) and the round became a little cagier at the half way point, he started feinting more but really only went on the attack and turned the heat up in the last 40 seconds. To some, the closing stages left a lasting impression and they scored it to Usyk(that's fine) to others AJ was winning more of that round and thought Usyk gave up too much of it without landing enough to get the nod(also fine).
Round 4, is the first round AJ started to make some meaningful adjustments of his own, he was feinting himself, moving better and found success with his own shots. AJ caught Usyk clean in this round, enough to firstly mark up his eye and eventually open up a cut around the eye. Usyk landed the punch of the round(I seem to remember good left hook in the second half of the round) but AJ did more damage to Usyk in this round and finished the round touching him with the jab several times(those still count and he was reacting to them). Roy Jones acknowledged AJ's adjustments and both he and Darren Barker gave the 4th to AJ in commentary.
You don't have to score either of these rounds for AJ yourself but you can't really argue if someone did is my point, because of the above reasons. Along with the fact that, plenty enough people have scored those rounds differently, to show they really were swing rounds.