Choose the correct verb forms to finish the amateur wizard's rather urgent diary entry.

If I ________ the instructions on the spellbook properly yesterday, I ________ as a giant talking frog at this very moment!

The correct answer is had read / wouldn't be sitting.

Here we have another classic mixed conditional. The mistake happened in the past ("yesterday"), requiring the past perfect ("had read"). The unfortunate result is happening right now ("at this very moment"), requiring the present continuous conditional ("wouldn't be sitting").