According to this page from the PMI about the PMP Credential, it's not 4500 hours of "project experience".
A four-year degree (bachelor’s or the global equivalent) and at least three years of project management experience, with 4,500 hours leading and directing projects and 35 hours of project management education.
In order to qualify, you should have 4500 hours in a leadership position for a project. I would have to look deeper into what this means, but I interpret this as serving in a position of responsibility. I would equate this to your organization's equivalent of what I've often seen called a software lead, a technical lead, a software manager, or a project manager.
I'm a software engineer myself. Even though I've worked closely with others, and sometimes have stepped up with additional responsibilities. However, just being part of a team doesn't mean you were a leader. Unless other people took instructions, direction, or mentoring from you, I wouldn't consider it a leadership role.