E.
Bless your heart.
First in my opinion you need to talk to the director about his teacher, that is her job to take of your child and if that means comforting him than so be it, that is what you pay for. He needs to feel safe and secure and if she's not making him feel that way, why would he want to stay.
My daughter was in a in home daycare until we moved to Texas and then home with me for six months before I went back to work. I ended up taking a position in a daycare office because I was so worried about leaving her. Because of my husband's work schedule she only had to attend daycare for two days a week and it was horrible at first, I would sit up in the front and cry. She would cry the night before thinking about it, then it got to be she would cry in the morning, and then she would cry when we drove in the parking lot, and in time I was able to leave her without crying. But, it did take about three months. But my steps each week got better and she had a very warm teacher who held her when I left and comforted her.
E., I believe you have to go with your mommy gut. Talk with the director, see if she can help, if the teacher is too busy when you drop off there should be someone who can at least go in and help for awhile, if that doesn't work then you may think about a diffrent center or an in home which would allow a little more attention.
My best wishes I know it is tough.