Improve Google Speed Insight score mobile

I have a Wordpress website for a Travel organization. 

I have installed several plugins to increase the speed of the website and need an expert to have a look at the settings. I do not have a technical background unfortunately.

I have installed the plugins Autoptimize , WP Rocket, Imagify. The plugins are free versions.

Score PageSpeed Insights is currently 37 and GT Metrix C(75%) D(68%) fully loaded time 3,8 sec. I can give a summary of the recommendations, also of GT Metrix. It is important that the adjustments will lead to a higher score without loosing any functionalities and images on the site and also no new plugins.

(Willing to use the paid version if necessary)
The purpose of the higher score is to increase the ranking score in Google. If I am satisfied with the job chances are that I will ask to have a look again once in a while. Any recommendations that will lead to a higher score I will consider seriously.



Love to get in touch with you.
Best regards,
Daan