I’ve turned off all plugins, emptied caches. My page setting are correct for https
Here’s my specs (with things on):
Operating System Linux
 Server Apache
 Memory usage 15.86 MByte
 MYSQL Version 5.6.34-log
 SQL Mode NO_ENGINE_SUBSTITUTION
 PHP Version 7.0.27
 PHP Allow URL fopen On
 PHP Memory Limit 768M
 PHP Max Upload Size 64M
 PHP Max Post Size 65M
 PHP Max Script Execute Time 30
 PHP Exif support Yes ( V7.0.)
 PHP IPTC support Yes
 PHP XML support Yes
 Site URL https://www.milsaver.com
 Home URL https://www.milsaver.com
 WordPress Version 4.9.4
 WordPress DB Version 38590
 Multisite No
 Active Theme WP Coupon 1.2.3
 Site Title MilSaver.com
 Site Language en-US
 Front Page Displays page [ID = 194]
 Search Engine Visibility 1
 Permalink Setting /%postname%/
 Active Plugins
 Advanced Ads 1.8.26
 All In One SEO Pack 2.4.5.1
 Autoptimize 2.3.2
 Breadcrumb NavXT 6.0.4
 Compress JPEG & PNG images 2.2.6
 Divi Builder 2.0.67
 Google Analytics for WordPress by MonsterInsights 7.0.3
 Gravity Forms 2.2.5
 Insert Headers and Footers 1.4.2
 List Custom Taxonomy Widget 4.1
 Really Simple SSL 2.5.25
 Redux Framework 3.6.8
 Relevanssi 4.0.4
 Shield Security 6.4.4
 Simple Custom CSS and JS 3.14
 SiteOrigin CSS 1.1.5
 Temporary Login Without Password 1.5.4
 UpdraftPlus – Backup/Restore 2.14.4.1
 WP External Links 2.2.0
 WP Fastest Cache 0.8.7.7
 WP Users 1.0.5
 Inactive Plugins
 All In One WP Security 4.3.2
 Sticky Menu (or Anything!) on Scroll 2.1.1
 WooCommerce 3.3.3
 WP-Optimize 2.2.2

Hi Sarah,
Is Visual Editor enabled? You can check this by navigating to WP Admin > Users > Your Profile and ensure Visual Editor is unticked. If it’s ticked, please untick it and try using your editor now.
If your Visual Editor is enabled or enabling it didn’t help, please disable CONCATENATE_SCRIPTS. This will require editing wp-config.php so if you’re unfamiliar with doing this I would recommend reaching out to your hosting provider for assistance.