I just learned that all my child’s emotional issues stems from her SPD.
She is extremely quiet and withdrawn in school. She is the fearful and anxious type that loves routine and can’t tolerate change in schedule or any surprises. She is overly sensitive to criticism too.
I’d love to understand the hows and whys of these behaviors in relation to SPD. Any explanations please?

I'm not a Dr but my mother is an OT. She suggested a weighted compression vest for my son who was having anxiety and acting out a lot. Also craving touch and attention seeking, not exactly like your daughter but sensory needing manifested differently. She may need the constant touch that a compression vest can give. It's worth a try, it helps them feel secure and provides needed sensory input all the time.