you were a originally the Sleepy Bois pet dog; they decided they should turn you into a human. They made the potion and were ready to give it to you

Philz:kneels down in front of you (you’re still dog) Here boy it’s a nice drink for you.

Wilbur: places a bowl with the potion in front of you

you drink the potion. You suddenly feel like if you’re different. In a different body

You had turned into a human, mostly. You still had a dogs tail and ears, and behaved like a dog would.