Understand the SEO stuff is different to website performance/speed. We have had some SEO stuff done in the past (adding meta tags to images, etc.), but not sure what more we can do and whether it is worth the investment.
We have a developer (contractor) who's good at implementing changes on the site, but he's not great when you need general improvements (e.g. the stuff above).
Site speed and SEO do
sort of go hand-in-hand. You'll be penalised in ranking for having a slow loading page/site.
First off - sign up for a free GTmetrix account which will enable you to run these tests from a London server. Right now you're testing a Canada-based connection, which isn't giving you realistic results.
Look into converting your jpgs to webp format - there are free WordPress plugins that will do this for you, but make sure you create a site backup before executing any of those… just in case.
Run GTmetrix on your catalogue and product pages too, don't just concentrate on the home page.
Other than that I'd say your site seems pretty light in terms of DOMs. Are you using any caching or CDN? If not then I suggest you look into these too - there's plenty of free/cheap solutions.
If it's still slow to load after all of that, then your hosts are shitty.