I'm not entirely sure what you mean in your first point....the site is (obviously) top for that term.
The point is that I get 42% of my traffic from referrals - social media, links to my website, advertising etc etc - and 49% directly, i.e. from seeing a link somewhere. And the stats are looking perfectly healthy. I'll bear in mind your recommendation, though.
That's what I mean, you're top for a term that nobody searches for. It's ultimately pointless and a waste of a site title.
SEO is free (minus your time) and doesn't take a lot of work. It's great that you're getting work from other areas and good SEO is not the only way to drum up business, but it's certainly a very useful one and unless you are booked up throughout the year without it then there is no reason not to invest a little bit of time into it.
As for the look of your site, I'm not a fan of full page sites as the large image size makes for a low res looking image.
I'd cut out some of your weaker images. The quality varies hugely so just keep your best ones to make a better impact.
The loading circle on the portfolio page makes it look like something will load beneath the images, but never does.
The HelveticaNeue font used for the menus looks untidy, I'd opt for something cleaner - maybe even just a change to all capitals would help.
The border around the images in recent work looks strange. Just the image with a small caption in a nice font would be better.
The whole blog would benefit from being full width, it would allow the images to be a lot bigger. The black border around the images is not pretty, neither are the captions. They'd be better off as images titles, displayed only when the user rolls over the image.
No images load on the home page of the site, when viewing on a mobile.