Well, I have an MBA and 1/2 a PhD and toilet training is still beyond me! It was a horrible experience with my daughter and my granddaughter. My sons seemed to do much better, but I also waited with them until they were almost three. I have great respect for you if you have developed a method that works! Don't let someone else make you feel devalued just because they have a document that they trust more than a person... it's classic for us academic types LOL!
Oh, and I'm glad to know that teaching swimming is as basic as daycare... both are actually quite complex, and despite having been a competitive swimmer in my youth, all three of my children learned to swim in lessons at the YMCA (and we have a pool, so it would have been convenient for me to teach them).
Chin up.... you KNOW you are doing a great job!