Hi Peter,
as you know we are not Google / SEO support.
but as you metioned you made few changes, now you have to wait like few other milions of websites for new Google reindex. It may take few days or weeks, nobody know why.
Using HTTPS for sure it was a good move from your side.
Your robots.txt file also looks OK.
My suggestions are:
- Create profile of that site in Google Search Console (old name was Google Webmaster Tools)
- Create a sitemap and add link to .xml link inside (1)
- Use some SEO online validators to check if everything is OK