Sounds like it may be slipping pretty bad but because it is an electronically controlled transmission it must be properly diagnosed with a scan tool to know exactly what is going on. With a scan tool you will be able to view when the pcm commands each shift. If the pcm is not commanding the shift and the reason it is late then there is a reason for it. If the pcm IS commanding the shift and it is not happening then the trans is likely slipping and possibly in need of replacement.