One way to increase ranking is to REDUCE BOUNCE RATE. Your bounce rate is too high. People will not stay on a site they cannot read. See image below:
your site looks like a meta engine. I couldn't see any advantages to using it over webjet or going straight to my preferred airline. You need to make you "unique selling proposition" clearer. At the moment my first impression is that you have built a "me too" site.
Please improve the site readability, you need to read some OFFSITE techniques first like using H1 tags , speed of the site and so on
I would like to point one key thing: keyword stuffing Try to reduce it the good thing is your website is optimized by Yoast SEO and well optimized in on page but would like to suggest you focus on the cotent part
First do best onpage of your website and add unique content to your website. Try to get good backlinks from some travel website with good seo strategy.