Child is 2-3 years old. Daughter is not potty trained, she gets hyster…

Child is 2-3 years old. Daughter is not potty trained, she gets hysterical just when I try to put her on the potty. Every time I put her in a doll's chair and show her how they write. My strength is gone ? Mother-in-law puts pressure that she's already big. She goes out in diapers all day, gives a sign when she wants to pee but pees in a disposable diaper instead of the toilet. She hid the diapers so she would feel uncomfortable wearing them while writing in her pants. She hasn't peed for 7 hours, holds it and endures. How to train her?