Improve website performance

Hello everyone,

I have my website working properly, but it’s slow.
I’ve done everything to improve and I can’t.

I have Jetpack and WP Fastest Cache installed.

I tried W3 Total Cache but the plugin interfered with payment processing and I had to uninstall.

When doing site analysis in GTMetrix, the result is that I have to:
Eliminate render-blocking resources
Avoid chaining critical requests
Avoid an excessive DOM size

Is there any plugin that helps me improve these fields?

I really want my site to be ok and I don’t know what to try anymore.

Thanks a lot for the help
Patricia

The page I need help with: [log in to see the link]