Copy existing WP site to new WP theme.

I need to add a new WordPress theme to an existing site. I have a site with many pages, posts, images, plugins etc that I need to change the theme on. The current theme is not suitable as it can not be upgraded to newer versions of WP and also is not suitable for viewing on mobiles and tablets. It was created for me originally so is not an off the shelf theme. I would prefer to use an off the shelf theme so that I can keep it updated and clean it must also be responsive for mobile and tablet viewing. I am prepared to purchase an off the shelf theme if required. You will need to make sure that all the content comes cross correctly, setting up the menus and categories as they are now. Everything must work as it currently does and you will responsible for making sure everything is set up correctly. You must back up all the data to make sure we dont lose anything. If you find a suitable theme then I will purchase that. I do not have time to spend all day writing or messaging with you I just want someone who will get on with it with the minimal of instruction and deliver a finished project. I have a spare domain/hosting that we can use for setting up and testing live to make sure its right before switching the theme over. Please note this site is within the online dating arena, it is not an online dating site but does have reference and links to such sites. If this is against your principles then please do not bid. I have not included the domain name here in an attempt to control auto-bidding and time wasting. Please message me for the domain name so that you can view the site prior to making a bid. Possible future work to come after this initial project.