Your daughter should remain facing the rear of the vehicle until her first birthday. The rear-facing mode better protects your daughter's head and neck in a frontal crash. Neck muscles typically don't mature enough to withstand crash loads until 12 months. Although your daughter may be above average in size, muscle maturity is more a function of age than size.
Our parenting advice is given as suggestions only. We recommend you also consult your healthcare provider, and urge you to contact them immediately if your question is urgent or about a medical condition.