Modify or does 2 wrongs make a right?!?

Back in Jan 08, in Johnston County NC, my ex and I came to our final custody agreement. At which time it became a joint/legal/shared custody as it was worded. We each had our son for a week at a time and an extra week each during the summer. Holidays were split and flipped depending on the year. In 09 though she moved out of state and our son stayed with me. I was very lenient about the holidays as being out of state she could not do the Court Ordered Custody Agreement as it read. Oh , I should add the papers also state he is to remain in the school district he is in currently unless we BOTH agree to allow him to move to another district. For the last 3 school yrs though he has been in school here, and she (the ex) still resides out of state. I am planning on getting married soon and want to move out of the county though. I KNOW without question he ex will not agree to me moving our son, since she would expect him to go there to her instead. To make this short…should I just move with him and not say anything until he is already involved in the new school, and housing situation/or should I filled to modify the agreement that the remaining in county/district be removed/ or just ask for it to be modified to the new district/county.
I know I would have a pretty good case to go for full /sole custody as she has not followed the agreement beyond the first yr of it, but my intention then nor now is to take / keep him away from her or her away from him.

Help confused and frustrated with this mess! ! !

If the consent order says the child is to remain in a specific place, then you should file a motion to modify if you want to move the child.