My trouble is always ending up with too much leftover whey.

Add some fruit juice to it, and sugar to taste. IMO it’s delicious. (Note: this works better with sour fruits. Lemon, orange, passion fruit, cashew, pineapple, this sort of stuff.)

I’ve never made paneer, but I have made a lot of ricotta (well, this type of ricotta, there’s also leftover whey ricotta, which I haven’t made). I had no clue paneer was basically just pressed ricotta.

It’s possible what you made is paneer.

At least traditionally, ricotta is the one made from leftover whey; that’s why it gets this name (ricotto = recooked). You make some low temp cheese like pecorino, re-heat the leftover whey to ~80°C, add some white vinegar (and probably salt), transfer the curds outside of the liquid and here you go.