You would have to use the same dropper for the flavorings, the VG and the PG for any prayer of being half accurate. I'm not going to try to say how many drops are in 25ml, because that is going to depend on the dropper.
I am going to make some huge generalizations to satisfy your question, but that's what they are.
Flavoring is usually PG based, so count that on the PG side of your equation. Strong flavor is 20%, light is 10%. Decide where you want to be.
Lets work on 100 drops, you can see how much of the jar it fills, and then just double or triple or whatever on the next count to get the 25ml.
Say you want 15% flavor, middle strength on flavorings. Put 15 drops of flavor in the 25ml jar. you want 75% PG? you already put in 15%, so add 60 drops of PG, and then 25 drops of VG. That is 100 drops, and 75vg/25pg with mid flavoring.
Keep that dropper, and you will know every time how many drops fill that 25ml bottle. Figure 5% possible error either way, as the temp of the liquids is also going to play a role in drop size.
Oh, and welcome back to the forum!