Searching (Filtering) XML by week in C#

Here is my code for filtering part. I am trying to filter appointments by week. I want my output to be like, when i am selecting a certain date from DateTimePicker it is going to display appointments for seven days (which is a week) starting from the date I selected. Please, I need urgent help. Deadline for my project is in two days. Thank you in advance.

private void loadDatabyWeek()
{
    listView1.Items.Clear();
    XDocument appointxml = XDocument.Load("appointments.xml");

    var appnt =
        from appoint in appointxml.Descendants("appointRecord")
        where DateTime.Parse(appoint.Element("date").Value) >= dateTimePicker1.Value.AddDays(-7)
        select new
        {
            Date = appoint.Element("date").Value,
            Time = appoint.Element("time").Value,
            Client = appoint.Element("cliName").Value,
            BMI = appoint.Element("bmi").Value,
            BodyFat = appoint.Element("bFat").Value,
            BodyWater = appoint.Element("bWater").Value,
            FatMass = appoint.Element("fatMass").Value,
            Waist = appoint.Element("waist").Value,
            Hip = appoint.Element("hip").Value,
            OtherNotes = appoint.Element("otherNotes").Value,
            Income = appoint.Element("income").Value
        };

    bool format = false;

    foreach (var app in appnt)
    {
        format = true;
        ListViewItem lvi = new ListViewItem(app.Date);
        lvi.SubItems.Add(app.Time);
        lvi.SubItems.Add(app.Client);
        lvi.SubItems.Add(app.BMI);
        lvi.SubItems.Add(app.BodyFat);
        lvi.SubItems.Add(app.BodyWater);
        lvi.SubItems.Add(app.FatMass);
        lvi.SubItems.Add(app.Waist);
        lvi.SubItems.Add(app.Hip);
        lvi.SubItems.Add(app.OtherNotes);
        lvi.SubItems.Add(app.Income);
        listView1.Items.Add(lvi);
    }

    if (format == false)
        MessageBox.Show("Doesn't Exist!");        
}