No worries.
Next time take your 9000 ft as your aiming point and calculate from there. You should end up there with Gdot ready for your arc.
To crosscheck how you are doing during descent also use the "official" Airbus formula:
Required Dist to descend = Diff. in FL / FPA
I.e. I am passing FL250 descending FL90 or 9000 ft like in your case so that's a Delta of 160 divided by what the bird shows, let's say 4° probably -> 40NM needed bare minimum distance. That's where all the psychometrics pain in the a°rs math tests come in handy
You can monitor you current FPA in Descent by occasionally going bird ON and see how you are doing.
As a general rule try to correct your descent profile while still far from the target as you will have many more tools, such as increasing your IAS and using speedbrakes. This combination can double your descent gradient when you're still far out and can afford higher rates of descent and speeds.
Below FL100 you will mostly be on a 3° descent on idle thrust, that you can increase by adding speed brakes and bring it up to even 7° by going full manual speed brakes at 250 kt but there are some threats involved in doing that (high rate of descent below FL100, manual flying with tunnel vision). So I would recommend to keep your AP on and accept the half speed brake of the A320.
During your next flight go Bird ON from time to time during descent and see how the aircraft behaves at different levels, how air density variations and wind changes affect your descent gradient. That should help
