Flutter E-Commerce Application has to be complete

I am looking for an experienced Flutter developer to build an e-commerce application for me. This application should have all of the features needed for a successful shopping experience, including a product listing, a shopping cart, and a payment gateway. I am open to suggestions for design, and I am aiming to have the project completed in 3-4 weeks.
My E-Commerce app is developed and working but I need changes in my App, this can be done remotely or at office.

It is just an bug solving, updating and maintaining our app