Bootstrap checkbox in line not aligned

I am trying to design a form but it is not being well formed. I need to make it responsive. But checkbox is not aligned well in horizontal.

<form class="ng-pristine ng-scope ng-pending">

  <div class="form-group">
    <div class="input-group">
      <span class="input-group-addon input_force"><i class="ti-pin"></i></span>
      <input type="text" id="mapInput" class="form-control input_force_text_edit  ng-pristine ng-untouched ng-isolate-scope ng-pending ng-empty" value="" g-places-autocomplete="" placeholder="Please enter drop off address WITHOUT Apt/Suite number" ng-model="order.drop_off_address"
      name="drop_off_address" autocomplete="off" validator="required" aria-invalid="false"><span></span>
      <input type="text" id="drop_off_address_line_2" class="form-control  ng-pristine ng-untouched ng-valid ng-empty" placeholder="Apartment/Suite etc." ng-model="order.drop_off_address_line_2" name="drop_off_address_line_2" autocomplete="off" aria-invalid="false">
    </div>
  </div>
  <div class="row">
    <div class="form-group" style="display: block; width: 100%;">
      <div class="col-sm-8">

        <div class="input-group" style="width: 100%;">
          <span class="input-group-addon"><i class="ti-mobile"></i></span>
          <input type="text" id="message_for_driver" class="form-control " placeholder="Message For Driver" ng-model="order.message_for_driver" name="message_for_driver" autocomplete="off" aria-invalid="false" style=" width: 100%;">
        </div>
      </div>

      <div class="col-md-3">
        <div class="checkbox">
          <label >
            <input type="checkbox" style="" id="is_ok_to_leave_at_the_door" class="form-control ng-pristine ng-untouched ng-valid ng-empty" checked="checked" ng-model="order.is_ok_to_leave_at_the_door"> Ok to leave at the door
          </label>
        </div>


      </div>
    </div>
  </div>

</form>

you can checkout my code over this URL. http://ift.tt/2uHWu1K