Hello, I am experienced BA, worked for many years for IT project. I am interested in your project. I will write BRD with necessary diagrams for the rest of your modules. I did similar job for my last client. I created BRD document for his web-based platform (over 100 pages), the document contains requirements analysis, use cases, processes swim line BPMN diagrams, web site map and wireframes. Please check portfolio section of my freelancer profile.
Please feel free to message me so we can discuss details of your project. I will be happy to dedicate my knowledge, experience and time for your project.