Build a checkout process for our website on Shopify according to our design

Hello! I am a managing director of a company called Simpleat. Simpleat is a new generation of healthy food balanced according to the needs of your body. We are selling our products via online shop based on Shopify platform. You can find our shop here Simpleat.me. The task that needs to be resolved: Organize a subscription model and a checkout procedure for our online store according to our design. The design is attached to the description of the project. We have the checkout working at the moment but it is based on Shopify plugin and does not correspond to our user friendly design made for their comfort and easy checkout. The purchase on our website can be done in 3 steps: Choose amount of bottles (on main page) ->Fill out the contact and shipping info, change quantity of product and way of buying (all in cart page) -> do the payment (at checkout page). In this process we need to build the second step according to our design and make the checkout work. The main difficulty is that Shopify is not so flexible to match our design that is perfect for users' comfort. I hope you are good at Shopify coding and can come up with the solution. So when your work is done I need to be able to make a purchase on website [login to view URL] and the page of the cart should look as provided in the design herewith and work according to the specification that I will provide to you. Please, let me know if you can do this work. I am available if you have any questions. Hope to start working with you as soon as possible! Marina Gribanova, Managing Director Simpleat Ltd.