19.18Solfège can help you

Since you learned fixed-do, keep that system for absolute note names:

C = до D = ре E = ми...

But for ear training, I recommend adding scale-degree numbers:

1 2 3 4 5 6 7

That avoids the movable-do conflict.

You can think:

“ми as a pitch name, but 3 as function.”

Example in G major:

B = си, but functionally it is 3.

That distinction is very useful.