The hosting company started providing Always On SSL with Let's Encrypt on Tuesday, so I applied for all my websites.
There are over 10,000 pages on wanichan.com, so it takes time to switch from http:// to https:// on Google search engine, so I did forcing to HTTPS using the .htaccess.
RewriteEngine On
RewriteCond %{HTTPS} off
RewriteRule (.*) https://%{HTTP_HOST}%{REQUEST_URI} [R=301,L]
You know, I have been maintaining my main website for over 18 years, so there are tons of moved files in the site. I had to replace each new place starting from http:// to https:// . - with Notepad. I did replace to https:// for every sitemap.xml as well.
Now I can set contact forms on my website.