I would like you to know that I have 5 years plus experience in Opencart and over all 10 years plus experience in web development. I worked in a software company 5+ years as web developer and UI developer. I was also interested in web designing, so I star learning Photoshop and now I am able to design a web site. For demo I am sending you a link buthemes.com where I worked as a web designer, UI developer and Opencart developer. I suggest you should hire a person who should not stuck on any stage of your project. He/she should be able to do needed changes (if any) in photoshop, HTML, CSS, JavaScript, Jquery, PHP and Database.