Couple pointers to increase your onsite SEO:
Alt tags - I see very few alt and title tags on your images and when I do see them they don't seem to be attacking specific keywords. Do so but not in a forced manner, keep it organic and relevant. For example your home page is title "Mobility Aids" yet that keyword only exists 5 times on the page and zero times in images titles or alts.
Also with your images you might want to consider naming the actual file something other than padlock2.png or things like this... That is a personal preference and I can't really back it up with data but I swear it'll help.
Your blog is a bit funky. The titles of the most recent articles are simply chapter numbers and tell me nothing about the content. It makes me not want to read them at all. You need to try and attract users with your content, not deter them.
Another article I randomly clicked was something about an Interview you did. This was the entirety of the article:
"Just got back from interviewing a mobility scooter user for tips and advice... Is there a better way to get advice than from someone who owns and uses a scooter. Probably not. Finished video coming soon."
That's it. It was posted in August. See right away as a user I feel like you aren't trying and don't want to return. I bet your bounce rate is rather high and length of visit rather low. These factors matter for sure. Engagement is arguably the most important thing when it comes to your design.
Speaking of design, it is kind of all over the place. I didn't really understand the layout and had trouble navigating. I looked for the blog which was found via a weird button at the very bottom of a very long wordy home page with weird formatting. At the top of the home page is a "usefull articles" button which goes to a page with a few titles that are underlined and say "read more" and then more links pop up and it doesn't even look like you can click the "read more" part because it's not actually a link but instead a clickable div and my run-on sentence here is an attempt to illustrate the confusion I experienced. Whew.
So I guess what I'm saying is you should focus more on improving the design, layout, and usability of your site. Please don't misconstrue my comments as demeaning or poking fun at your site. It isn't terrible at all. I just think addressing the issues I've pointed out might actually go a long way to improving your ranking. The social stats are great but if users land on your site and leave immediately due to poor UX then it's all for not.
Hope this helps. Don't give up!