Wow, that is one colorful SS. I've got to say it makes my brain go SPLAT too! And I've been looking at these things daily for almost a couple years now, LOL.
I'd say 1.5 seems too high, you know that from the cycles where you got a number to low to shoot at the next shot time. So you are actually in pretty good shape I would say, it's just a matter of doing some experimenting & data gathering to figure out what dose actually works, and you've already got the high end nicely bracketed.
If the 0.75 lands you in higher #s over the next cycle or two, I'd probably try something like 1.25 and see where that lands you. I'd lean more towards thinking the 1u was too low, as flat #s often mean the dose is too low. But really it's kind of a toss-up, you a try a dose change and see what happens. If you get a nice nadir tonight and good PS in the morning, then you went in the right direction on the dose. If the #s just run higher overnight, then you try the other direction.
On the topic of dose settling you can get varied answers, but basically there are two patterns I have seen:
1) They get a good response on cycle 1 but lose that on the following cycles.
2) They don't get much response on cycle 1, but get a better response on cycle 2, 3, or 4 if they get a little overlap between doses.
ECID applies though, and some cats seem to do better on a steady dose, & giving it a few days to settle in. Personally I like holding a dose for 2-3 days (or longer if the data isn't clear or there are practical concerns, like you won't be home to test) when you are on a dose increase path.
If you get mid-cycle #s below 50 or PSs below 150, you want to lower immediately. No dose holding in that case. It's more when you are increasing doses, you want to wait a couple cycles to really see how the dose is working for them before embarking on your next increase.