I wish you had posted a photo or your age to assess the upper cheek flattening. It sounds like you may benefit from Sculptra in the mid-face which would gradually build up the collagen and last for two years. Another option is Belotero in the under eye area which is a much thinner hyaluronic acid filler and perfect for the delicate area under the eyes.
Cannula Technique for Under Eyes in New York City
Yes, the cannula technique is the safest method of lower / under eye filling. I use this technique when using filler and with fat grafting for this area. Restylane and Juvederm Ultra are great products for this area.
Fix for those under eye hollows
I routinely perform Restylane injections for treatment of "tear trough deformity" with costs starting at $250.