Am I a candidate for Invisalign? Have had braces in the past but want to correct protrusion. (photos)

Hi. From the photos posted it appears you are currently under clear aligner treatment (invisalign). The side photos show that the upper teeth are not flaring out and are following the natural slope of your upper jaw (maxilla) and gums. Therefore, orthodontics will not further correct what you feel are protruded teeth as their position is in the proper position.
What may actually be bothering you is the tooth size discrepancies amongst your smile teeth. This make your front two central incisors seem larger and more prominent.
Once your Invisalign is completed and the neighboring lateral incisors are no longer set back and rotated and the front centrals are rounded into arch it may appear less noticeable. If it still bothers you at that juncture, consider porcelain veneers on the upper 8-10 teeth.