As has been noted in other comments, running a business is not a project in itself.
That being said, anyone who has built a business from scratch has performed many projects in order to get the company off the ground.
In order for you to import the clothing you would have needed to perform some financial planning, risk analysis, communication plan with stakeholders, provide a timeline for when shipments would be ready for resale, and so on. Once you are up and running, then yes the project is over and you are in maintenance mode, but adding a new sales line or opening up a new market would be another new project.
Even smaller things like setting up your store/office involved materials requisition, contracts, and so on.
The only snag I see here with you claiming your experience is if you were a sole proprietor with no partners or employees. PMI will require "a colleague, peer, client or sponsor who has intimate knowledge of the project verify this experience" for your application.
My advice to you is, if you haven't already, document everything you did to set up the company, and go through the PMBOK to see which domains those activities represented. You need some experience in all domains, so just managing forecast spreadsheets and sales cold calls won't cut it.
Best of luck.