Our site is Hosted by Shopify (a large online Host for small business sites) and has been since mid October of last year. Our online security, storage, and function of the website and Checkout is entirely provided by Shopify which thanks to it's technology roots function and size is about as safe as a site can be.
Websites that sell online use SSL technology to protect the information being shared. Heartbleed is like an opening in the SSL system that could let an outsider get to that private information.
Shopify has addressed this issue already and in an email provided this assurance "we want to stress that merchants and their customers using Shopify are safe from Heartbleed".
I believe our site thanks to Shopify is safe from this threat.
I do suggest caution using some websites and looking into the Google Chrome extension for your browser called "chromebleed Checker" which warns of Heartbleed.
You may also want to change your passwords and watch bank statements for anything unusual, which you should do regularly anyway.