List posts by taxonomy tag, in reverse order?

I’m using a slightly modified version of the code from this post (closed thread or I’d ask there): https://www.ads-software.com/support/topic/list-posts-by-taxonomy-tag?replies=8

Here’s my code, from my sidebar:

<br><?php
$post_type = 'portfolio';
$tax = 'portfolio-date-of-project';
$tax_terms = get_terms($tax,'hide_empty=0');

//list everything
if ($tax_terms) {
  foreach ($tax_terms  as $tax_term) {
    $args=array(
      'post_type' => $post_type,
      'suppress_filters' => true,
      "$tax" => $tax_term->slug,
      'post_status' => 'publish',
      'posts_per_page' => -1,
      'caller_get_posts'=> 1
    );

    $my_query = null;
    $my_query = new WP_Query($args);
    if( $my_query->have_posts() ) {
      echo "<h2 class=\"tax_term-heading\" id=\"".$tax_term->slug."\"> $tax_term->name </h2><ul>";
      while ($my_query->have_posts()) : $my_query->the_post(); ?>

<li><a href="<?php the_permalink() ?>" rel="bookmark" title="Permanent Link to <?php the_title_attribute(); ?>"><?php the_title(); ?> - <?php echo get_the_term_list( $post->ID, 'medium'); ?></a></li>

        <?php
      endwhile;

    }
    wp_reset_query();
echo "</ul>";
  }

}
?>

I’m having a few problems.

First, I’d like to show this list in REVERSE order, since the tags are actually dates, like “2009” and I want the latest date to show at the top.

Second, the code doesn’t seem to be showing on my category archives:
https://www.ianaleksanderadams.com/blog/ for example.

I also want to put these in drop downs, but I think I can figure out that formatting once I get some help with those issues. I tried putting in that supress code above, but I’m not sure what else will help them show up in the categories.