I purchase a lot of gigs on Fiverr for 5 years. Here is my points.
1, Buy from real people with a real photo. For example, your forum picture is much more real than your Fiverr account.
2, How do you prove the gig pictures are from you, not copied from the internet? If I don’t know how to use photoshop, I could also create a seller account like yours now.
3, Not only show your portfolios, but also show how you work and how you getting things done. Result is important, but if you make the process transperant and clear, that would be much more convinced for your potential clients. You could use a video to explain how you work for your clients.