6 months post-op. What can be done to fix my animation deformity? Should I downsize the implant? (photos)

First it is important to understand the cause of animation deformity: The pectoral muscle is partially detached, and the cut edge of the muscle then heals into the scar capsule around the breast. You are correct that animation can persist after moving the implants in front of the muscle unless the muscle is re-attached. Another option is to convert to the split muscle plane; this preserves muscle coverage over the upper part of the implant but moves the lower part behind and re-attaches it. 

Thank you for your question.  This is a difficult problem and should be best discussed with your PS.  Animation will usually improve with either implant removal or placement above the muscle.  An alternative if the muscle has been released fully in the first surgery is to denervate that segment as it is not contributing to your physical strength at that point anyways.  A recent article in our PS journal has described this option well.  It is really difficult to reattach the muscle back and options include using allograft such as processed cadaver or pig dermis (expensive) or a rectus fascia turnover flap.  Based on your photos it also appears that the implants are not expanding your lower poles very well at the six month mark and the areolar incisions seem indented.  
There is no substitute for an in person consultation with a board certified PS and I would go back to your original surgeon for a review of the shape and the retraction.  If they are unwilling or unable to fix this, then a second opinion is best.  

Obviously, an in person exam would be the gold standard.  That being said, you appear to have tuberous breasts with a short constricted distance between your nipple areola complex and your inframammary fold.The muscle animation deformity you refer to is apparent, but in my opinion is not your main problem.  I totally agree with your personal plastic surgeon that you needed a periareolar incision, but possibly there was inadvertently not a complete release of your constricted subareolar tissue.  At this point, I don't think your considering going on top the muscle is appropriate, especially considering complications that occur from supra pectoral implants.  At this juncture, I believe you should go back and discuss further release of your constricted tuberous breasts with your personal plastic surgeon.