Can anyone help with the below:

I'm trying to stop this trigger from creating an extra object every time the Opportunity page is updated.


trigger createPMPage on Opportunity (after update) {

    List <Project_Management__c> PMInsert  = new List <Project_Management__c> ();
  
 
for (Opportunity o : Trigger.new)
    {
         Project_Management__c p = new Project_Management__c ();


  if (o.Job_Type__c == '1' )
    
        {
   p.Project__c = o.Id;
         p.Name = o.Name;
         p.OwnerId = '005b0000000hZc9';  
         if( o.Stage_One__c != Null){
             p.Stage_five_Invoice__c = 'Ready to Invoice';}//end if
        }//end if
      
        if (o.Job_Type__c == '2'  )
        {
        p.Project__c = o.Id;
  p.Name = o.Name;
        p.OwnerId = '005b0000000hIRM';
        if( o.Stage_One__c != Null){
             p.Stage_five_Invoice__c = 'Ready to Invoice';}//end if
        }//end if
      
         if (o.Job_Type__c == '3'  )
        {
   p.Project__c = o.Id;
         p.Name = o.Name;
         p.OwnerId = '005b0000000jCjP';
         if( o.Stage_One__c != Null){
             p.Stage_five_Invoice__c = 'Ready to Invoice';}//end if
        }//end if

      
        if(trigger.newMap.get(o.name) != trigger.OldMap.get(p.Project__c)){
         PMInsert.add(p);
         }

  }//end for

  insert PMInsert;
     }//end trigger