Hi Vanessa. I LOVE your art!
The thing I see here is site map/content hierarchy.
Your art is frankly awesome. Why hide it behind 4 big category pix. Most visitors don't know you, so breaking the flow in taking a decision right upfront is asking a leap of faith right away.
I would put 12 to 16 products on the home page, THEN 4 blocks offering to "explore more" by categories.
Doing so also allow you to switch Portfolio and Shop in the header. (Portfolio yet present another leap of faith.) And I would rename "shop" with something along the line of "Artworks" or "My work".
That way, the site would present content in this way:
1 - Home: with a selection of your finest work.
2 - My Work: without clicking on it I understand there's more good stuff behind that button.
3 - Portfolio: ok, there's so much stuff here that there's a portfolio... even more good stuff to discover!
A hero banner with something beautiful might work but do not make it so we have to scroll to see the first products row.
My 2 1/4 cents.