As an aesthetic dentist who is an elite provider of Invisalign I would suggest a refinement scan/molds taken and a decision should be made if anymore movement could correct some of your concerns regarding canting or slants.In regards to the concern of some teeth being larger than others, many times a combination approach to Invisalign is utilized that includes alignment with Invisalign, whitening procedures, aesthetic bonding procedures and veneers to give proper size, shape, color and symmetry to a smile. Orthodontics has its limits. Aesthetic dentistry stretches those limits that are set by orthodontics alone. This is why a general dentist should always be the main provider of treatments they feel comfortable treating or at minimum be the quarterback of all dental treatments.good luck!