3.5 year dd very shy, timid, not assertive

[Intjmum]

Hi mums,
Am worried about my preschooler dd’s shy and timid nature! She’s so talkative ,fun and assertive at home with us( mum and dad) but outside she goes into her shell. She won’t answer any body’s questions, looks at the ground or hides behind us, and if we push her then she mumbles softly. Even in her nursery teacher said that she tags along with friends and is quiet in class. She tells me that her ‘friends’ hit her or snatched her toys. Hv told her to stand up for herself, but she doesn’t have the courage I feel. Have seen her with other kids on playground, she gets left out, waits for her turn on slides but even a 2 year old can push past her or snatch her toys and she just stands there with a sad look on her face, but doesn’t fight back and then whines. Need help to make her assertive and speak up loud and clear, to avoid being bullied. Thanks

[Intjmum]

Hi 👋🏻???? Anybody there???would love suggestions and advice to deal with my situation.