Magento – Home Page OwlCarousel How To Control What Products To Display

There's a widget for that! In your CMS page,

{{widget type="catalog/product_widget_link"
         anchor_text="[Optional: CUSTOM LINK TEXT]"
         template="catalog/product/widget/link/link_block.phtml"
         id_path="product/223552"}}

Then customize app/design/frontend/base/default/template/catalog/product/widget/link/link_block.phtml. I use something like this:

<?php

$_product = $this->getProduct();
$_image = '';
$_price = '$' . money_format('%n', $_product->getFinalPrice());

if ($_product) {
    $_image = Mage::helper('catalog/image')->init($_product, 'thumbnail')
        ->keepAspectRatio(true)
        ->keepFrame(true)
        ->resize(115,115)
        ->__toString();
}
?>
<div class="item">
    <a <?php echo $this->getLinkAttributes() ?>>
        <img src="<?php echo $_image; ?>" alt="<?php echo $this->htmlEscape($this->getAnchorText()); ?>" style="border:0" />
        <?php echo nl2br($this->htmlEscape($this->getAnchorText())); ?><br />
        <b><?php echo $_price; ?></b>
    </a>
</div>

Block shortcode should have an option to specify products count. Usually it is product_count

Try to update code to

{{block type="catalog/product_list" column_count="4" category_id="3" product_count="12" template="catalog/product/list-officestationery.phtml"}}

Please note that chosen category should contain enough products.