Once you get close to what you want for a charge, lets say start is 4 and max is 5gr of powder Y and 4.5 shoots best for you, try
both increasing and decreasing the OAL a little. (assuming your not at MAX charge)
In general my pistols seem to like shorter a little better, but on occasion they like longer better.
Bullets make a difference as well. I have had better results with 124gr RMR FMJ or MPR JHP from Rocky Mountain Reloading than say with a 124 Xtreme plated. (RMRs plated shot better for me as well)
My guns seem to like 124s better, some seem to prefer 115s.
Sometimes my 1st powder choice is great, sometimes it stinks.
Been there
Also some guns just seem to like some powders better, they all just have a mind of their own.
If you haven't yet it is worth trying (in a range for 9mm) a faster powder say Sport Pistol, HP38/W231, AA#2 etc. and a medium powder WSF, Universal, Unique, etc, and something slower BE86, CFE-P for example if you are just after "fun" ammo.
If your after max velocity then things on the slower burning side are better.
For light-medium "fun"loads sometimes keeping things subsonic say below or at around 1050fps helps.
My favorite match load at the moment is 4.4gr of WSF, RMR 124gr MPR JHP @ 1.08,
comes in around 1030-1040 fps.
I want most of my practice ammo to be about the same as match ammo about 128-130 PF. (I do load Full power stuff for practice as well)
So usually I am working in a limited area of the charge range, but I usually step 2/10 of a gr and do a ladder around the range I am after, then 1/10. Test shorter and longer OAL.
While I am at it even though I know it maybe more velocity than I am looking for I will ladder min to MAX at .2 as well.
I have 5 different 9mms.
What works really well in one generally works well in the others, 2 of them sort of agree on what works best, the others prefer something different for best,
but with a good load the shooter (me) is more of a factor, ie I can't always shoot the difference between best and good loads.
The ones the guns don't like, they just don't like and I can shoot the difference between don't like and good all the time.
Initially I usually load 15 of each, 5 to chrono and 10 to shoot two 5 round groups.
I
So after all the bla bla bla I wish I could say bullet X with powder Y at OAL Z would work best for you, but all guns are different,
and that's part of the fun of reloading, finding the one load that works best, sometimes the journey is more fun than the destination.
(and sometimes you make a wrong turn)