SEO with Squarespace website and FB gremlins

I have built a Squarespace website which I found difficult and really frustrating but I'm fairly happy with it.
I have 2 main issues...
1. visibility in search engines - I have followed the SEO checklist on the Squarespace help page (not sure how well I have done this though!!) and am now a bit stumped. Google analytics reports that I am appearing on average 38th for my main key words and even poorer for other key words when I would expect to be ranking much higher in search results.
2. sharing content to Facebook - my content isn't sharing properly to Facebook - Squarespace tell me it a Fb problem but I can't seem to find any support form FB.
I could also do with a bit of feedback about how my site looks and what I could do to improve it.
Here's the link for my website...
https://debdaysewingroom.com
Many thanks
Deb