Aw nako, totally understandable ang alala mo, a few of us moms worried about the same thing when our babies were around that age, kaya you're not alone dito! Honestly, anti-flathead pillows can help, pero mas importante talaga na i-vary mo ang position ng baby throughout the day, try tummy time (supervised, of course), alternating which side he sleeps on, at carrying him instead of always leaving him on his back. Since the flattening is already noticeable on both the back and right side, I'd really suggest checking with your pedia first para ma-assess nila properly if he needs any intervention or just monitoring lang, because sometimes babies' heads round out naturally as they grow, but better safe than sorry talaga! Some of my mum friends like using memory foam pillows designed for babies (look for ones that distribute pressure evenly), but again, position changes throughout the day are honestly the real game-changer, mas effective pa kaysa any pillow alone.