[SalesForce] Updating lookup field on a custom object using another text field as a reference

Very new to coding and need a little help populating a lookup field.

I have object Account and custom object Order__c. On Account we have a Ship_to_Code__c which stores an ID. This ID is also part of the custom Order__c object, Ship_to_Code_del__c

Orders__c has a lookup to Account. When creating (or importing from dataloader) an Order__c record, I would like to auto populate the account lookup field with the Account name where there is a match on the ship to code IDs.
My code below is running without errors, but not returning any account names in the lookup field. I suspect its something to do with line 16 and not correctly asking for the account id value:

trigger TestOrders on Order__c(before insert, before update, after insert) {
    set < string > setIds = new set < string > ();
    Map < String, Id > mapMatch = new Map < String, Id > ();
    for (Order__c Order: Trigger.New) {
        setIds.add(Order.Ship_To_Code_del__c);
    }
    for (Account acc: [Select Id, Ship_To_Code__c from Account where Ship_To_Code__c IN: setIds]) {
        mapMatch.put(acc.Ship_To_Code__c, acc.Id);
    }
    for (Order__c Order: Trigger.New) {
        if (mapMatch.containsKey(Order.Ship_To_Code_del__c)) {
            Order.SFDC_Account_Name__c = mapMatch.get(Order.Ship_To_Code_del__c);
        }
    }
}