It helps if you post a photo. Being a new quilter, you might have difficult just doing that small of a border. Have you looked into doing a folded border?? I know that EB of Quilt in a Day may have a video on making them. The fold border just won't be as stretchy as a single layer border might be. They can be tricky. Hopefully, a LAQ will give you advice on how to handle the concern you have about a flange border.