hi, as an occupational therapist I think you should continue physiotherapy if you have seen a good results. I don't know the exact situation of your child but I know that in these cases more work and practice will make more results.
don't forget sensory stimulation if your child has sensational or tactile problems in her arm...
her hand move back side during movement position, and she can not move her hand back side from elbow after resting her hand on chest. physically both hand are seen same i.e. blood circulation o.k. groth o.k. etc.
I think you should continue to physiotherapy, pls practice all of exercises every day and more than one time a day, consult with an pediatric occupational therapist too about needed sensory stimulations on the arm. your baby would be better on 8-9 mounts but not completely you should follow the treatment.
good luck!