Help with test class for field update trigger

I need a litte help with what to to to get better test coverage for a trigger that updates a contact record field with the name of the last campaign event attended. Here is the trigger code:

trigger LastEventAttended on CampaignMember (after insert, after update) {
    for(campaignmember cm : trigger.new){
Contact con = new Contact();
List<CampaignMember> cms = [SELECT ID, CampaignId
                            FROM CampaignMember
                            WHERE ContactId   =: cm.ContactId
                            AND Status        = 'Attended'
                            ORDER BY Campaign.EndDate DESC
                            Limit 1];
        if(cms.size() > 0) {
            Campaign camp = [SELECT Id, Name
                             FROM Campaign
                             WHERE Id   =: cms[0].CampaignId];
            con = 			[SELECT Id
                             FROM Contact
                             WHERE Id   =: cm.ContactId];
            con.Last_Volunteer_Event__c = camp.Name;
            update con;
      }
   }
}

and here is where I am at with the test class. I am getting 45% coverage:

@isTest
public class LastEventAttendedTest {
//create a contact
static testmethod void createContact() {
    Contact c = new Contact();
   	c.FirstName = 'John';
    c.LastName = 'Doe';
    insert c;
//create a campaign    
    Campaign cm = new Campaign();
    cm.Name = 'Acme Campaign';
    cm.StartDate = date.Today();
    cm.EndDate = date.Today();
    insert cm;
    //add the contact to the campaign with the status of "Prospect"  
    CampaignMember cpm = new CampaignMember();
    cpm.ContactId = c.Id;
    cpm.CampaignId = cm.Id;
    cpm.Status = 'Prospect';
	insert cpm;
    //add the contact to the campaign with the status of "Attended"    
    test.startTest();
    cpm.Status = 'Attended';
    insert cpm;
    test.stopTest();
    } 
}

Where I seem to be missing coverage is in the IF statement of the trigger wher it's querying for the campaign and contact. I have tried a number of things but unsure how to proceed. Any help will be appreciated!