Teaching in preschool is by far the most rewarding and most challenging teaching experience I have had. I was a state athlete for swimming, we trained twice a day, 7 days a week and that was easy compared to my short, challenging, but super rewarding preschool stint. What you are doing is awesome, you are the child's first and most memorable teacher. My daughter comes home every day and tells me her favorite person is her preschool teacher.
You would not believe how many people think being a preschool teacher is just being a baby sitter. These people do not know what we are actually doing in the classroom and that we are actually teaching the students in the classroom.
It's funny, they want teachers to teach and yet see them as baby sitters. I have no idea how that logic works sometimes. That being said, keep being awesome, I'm sure the children are super blessed by you.