The method getAttributeText looks like this:

public function getAttributeText($attributeCode)
{
    return $this->getResource()
        ->getAttribute($attributeCode)
            ->getSource()
                ->getOptionText($this->getData($attributeCode));
}

Notice the last 2 lines.
They mean that the method calls getOptionText from the source model class.
I see that your attribute has a custom source model npm_recurrex/package_source. Make sure that model has the method getOptionText or it's parent class has it and returns what your need.

The method getAttributeText looks like this:

public function getAttributeText($attributeCode)
{
    return $this->getResource()
        ->getAttribute($attributeCode)
            ->getSource()
                ->getOptionText($this->getData($attributeCode));
}

Notice the last 2 lines.
They mean that the method calls getOptionText from the source model class.
I see that your attribute has a custom source model npm_recurrex/package_source. Make sure that model has the method getOptionText or it's parent class has it and returns what your need.

[EDIT]
Your getOptionText is wrong.
It would work if the attribute would be of type select.
But it doesn't work for multiselects.
Here is a scenario. Actually I'm using your scenario.
$_product->getData('package') returns 1,2.
And I assume your options are something like this:

$options[] => array('value' => 1, 'label'=>'Option 1');
$options[] => array('value' => 2, 'label'=>'Option 2');
$options[] => array('value' => 3, 'label'=>'Option 3');
$options[] => array('value' => 4, 'label'=>'Option 4'); 

In this case, your method receives as parameter 1,2 and you check if there is an element in $options with value = 1,2. and there isn't.
Try to make your method look like this:

public function getOptionText($value)
{
    $options = $this->getAllOptions(false);
    $optionsByValue = array();
    foreach ($options as $item) {
        $optionsByValue[$item['value']] = $item['label'];
    }

    $values = explode(',', $value);
    $returnValue = array();
    foreach ($values as $_value) {
         if (isset($optionsByValue[$_value])) {
             $returnValue[] = $optionsByValue[$_value];
         }
    }
    return implode(', ', $returnValue);
}

Untested code so look out for typos.