I would look into shadowing both an OT and PT. Also, I would broaden your thoughts of PT and OT because as you progress through school you may want nothing to do with CP kids and this could potentially change your view on OT and/or PT as a career.
Personally, I did not even know what OT was when I attended PT school. I chose PT because I was interested in healthcare, weight training, problem solving, helping people, having the ability to change practice settings, demand for the job, having a good lifestyle (read: not on call, not working odd hours, etc.) and I initially wanted to work with athletes.
Now that I know what OT is I still would have chosen PT because I can treat any joint in the body without restriction where as OT is primarily(but not always) focused on the upper extremities.