Hi Good day.
You child is experiencing the normal aches and pains of separation anxiety.
She most likely is crying not because something went wrong but because she misses you and feels the loss when dropping her off. I like to suggest that shorter goodbyes work well as the longer they are the more anxiety builds up for her.
I understand your desire to stay with her a while longer but this sends the message that if she cries long enough you will stay thus making the separation that much harder.
If she senses your confidence she will begin to rely on that and her own confidence will develop and drop off will get easier. I am also interested in knowing how the teachers are helping you with this. This is not a new experience for them so they should be able to provide the comfort she needs and distract her with fun learning games after your departure.
The teacher needs to have as much patience as it takes. It is hard to predict how long it will go on but I definitely recommend short good byes and a sign of strength and reassurance from you. Some kids take longer to separate but it will happen if you stick with it. You are not harming her in any way and this is part of normal development.
The more you give her this independence now, the better off she will be as she continues to mature.
I do know of parents who pulled their children out only to have continuing problems year after year after year, but that is a judgment call only you can make as you know what is best for you and your child. I can only reassure you that this is normal separation anxiety and this stage gives her some very necessary skills for the rest of her life.