Well done! Just like you, I felt relieved getting that certificate and being able to think “I just did that, that’s awesome.” Kudos on a first time pass!
It sounds like you had an eventful checkride and got the opportunity to figure out a really good study habit. DPEs can be hit or miss unfortunately, sometimes they will be in a really good mood one time, and something might just trigger their emotions the next. I’m glad you got a great DPE (it sounds like), I for one enjoy the DPEs that make the environment safe, and remind you that perfection will not happen, which puts you at ease. We are all human, we make mistakes…the biggest advice forward for the future checkrides is constantly talking through everything. Recognizing and taking corrective actions will demonstrate that you understand thoroughly the maneuver or reference to instrument flight (going to IFR)…it’ll payoff in CFI as well!