Welcome! Ben (6.5) was born with tort/plag also, along with windswept hips & feet, scoliosis, etc. He's always been behind, started therapy right after he was born, and is still in therapy today. It doesn't stop him, though, from being "normal" most of the time. He's 1-3 years delayed, depending on the skill, and this also carries over to the muscles of his eyes, digestion, etc. He's a really big kid (always 95+% for everything), so it's odd to see him compared to both 8 year olds and 4 year olds on the playground or whatever. He does get frustrated at times, but mostly, he just keeps on keeping on. His therapist told us that he's progressing at the same rate as all the other kids, but he's behind them, so they continually stay ahead of him. She also said that there are no "new" motor skills to learn after about age 9-ish. You just use the teenage years to perfect the skills you learned in early childhood. He'll probably finish therapy when he's 9-10 based on her projections. We really don't know.
He also has Asperger's, attention deficit, and profound giftedness. This combination with delayed motor skills is the reason we've chosen to homeschool him. We can tailor his needs to his strengths and weaknesses. Even at home, the differences are occasionally very frustrating for him, but he'd have it no other way, and 99% of the time is very happy.
Your dd will probably catch up, but even if she doesn't, everything will work out just fine!