Hey There
Certified Wordpress/WooCommerce expert here with 7 years of exp.
I'm rank #2 here in wordpress category among 15 million+ freelancers . You can verify the same here: https://www.freelancer.com/d/skills/Wordpress/
You can check my profile here :
http://www.freelancer.com/u/sonuinfy.html
I'm clear with your requirement of optimizing the design and layout of your existing website to make it responsive so that it can be viewed across desktops, mobiles, tablets etc. I use Bootstrap framework for perfect responsiveness and it is considered best practice by Google as well.
Hope to hear from you soon..
Regards,
Gaurav