STEM stands for science, technology, engineering, and math. Women in STEM refers to women in these fields. This phrase comes up to represent women in traditionally male-dominated roles.
Take time each day to remind yourself of what you do know, acknowledge things you did right, and above all, be kind to yourself as you figure things out.
The best thing I can say is if you feel there’s no one, ask anyway until you find someone. Also, a mentor doesn’t have to be in the same industry or job as you.