I'm thinking of taking this opportunity to get forehead fillers.

My forehead line has always been flat and slightly sunken, so whenever I look in the mirror, that's the only spot I notice. I'm thinking of getting forehead fillers this time. However, now that I'm actually deciding to get the procedure, I'm scared that the shape might look unnatural or that it might disrupt the overall balance of my face. I'm worried that if I get too much injected, it will stick out like a "Gangnam Sister" and look artificial. I'm also concerned that the filler might not be able to withstand the weight over time and sink down. I'm also wondering if side effects are common, such as specific areas hardening unevenly when I make facial expressions or leaving marks because the molding didn't work properly. I've heard that payments are usually made in 1cc increments, but I have no idea how much volume to use to match my facial bone structure without it looking excessive.