Your TTFB is not good, thats the problem.
When I call your page, every static asset (which are cachable at CloudFlare) do have a TTFB of 50ms.
But your dynamic request (your HTML) takes 2 seconds. As this is not cachable by CloudFlare.
You are using WordPress which is not really well known for performing good, but rather for beeing easy to install and implement.
But the good ponint about this is: you can just use any good Caching Plugin which will statically cache your Pages and delete on change. Thats what I would recommend here. After this you please measure again with GTmetrix or with Google PageSpeed Insights