I looked into your site's theme a bit further and it appears you're using the Kids Voice School theme (link) - which was built to be responsive.
Responsive themes offer an easy way to set up a website that looks great on any device - that includes your desktop computer, laptop, tablet, or mobile device. Also, responsive themes remove the need to have a specific mobile-only theme - the theme will respond to the device viewing the content and resize and style the content accordingly.
If you still choose to use this theme in addition to Jetpack's mobile theme, please copy your code modifications to your theme here and indicate what files you changed and we can try to help. Also, since the Kids Voice School theme is a paid theme, you should also be able to get help from the theme developer to see why your Front Page Display didn't work.
Let me know if you have any questions.