You can't resist your own magic and give in to the urge to enter the restroom. You know your fate, and can only watch the mirror as your changes begin.
Your body shrinks and becomes much skinnier, as you skin becomes smooth and your shoulders narrow. You watch as your hair pulls back and begins to lengthen as your face permanently adopts more feminine features. Your shirt changes from white business attire, taking on the slightest shade of pink as it changes to fit your new womanly frame. Most notably you feel a pressure on your chest as a bra forms to hold your new breasts.
The last of your clothing changes occur as your pants become a neat skirt and your shoes expand into high heels. A soft tug between your legs welcomes you to your new gender.
Through the spell's magic, a purse appears on the sink containing your new ID has well as your makeup and hygiene products. You touch up your lipstick, wondering if you should take a moment to make yourself look nice while you're here in the women's room.