Hello My Friend,
I have written requirements documents over the past 15+ years and will assure you that just user stories will cause your project to fail. You have two types of requirements: Functional and Non functional. The non functional requirements can be at business level and can be more technical.
The user stories can be either in short form as you see in internet (As a < persona >, I want < to achieve > so that < this can happen >) or can be in the format I write (Epic-Story ID, Description and Scope, Actors, Inputs, Precondition for success, Basic Flows/ Scenarios, Post Condition, Other Flows/ Failure Flows and Scenarios, Dependencies/ Impact on other areas, Constraints, validation and business rules).
Again, just writing user stories will not help. You need to write epic catalogue and associated wireframes.
I have several examples both in PRD format and in User Story format. Do let me know how I can help you.
Thanks and Regards,
Chandana.