Should I go over or under the muscle? (Photo)

You won't get consensus even among surgeons on whether over or under the muscle is better. My preference is always under the muscle as it has less chance of capsular contracture, and less chance of rippling and implant visibility. But best to find a plastic surgeon you like and trust and go with their recommendations. All the best

There are advantages and disadvantages to both subglandular and submuscular placement. I typically recommend submuscular implant placement for patients who don't have a lot of their own breast tissue to "hide" the implant (this isn't you). I typically recommend subglandular placement for patients who who use their chest muscles for strenuous activity like CrossFit because forceful contraction of the muscle over time can displace the implant. When there isn't a clear reason to choose one location of the other I tend to recommend sub muscular placement because it tends to look more natural and there is a lower rate of capsular contracture over time.