Misshapen head

So, I’m at a loss. My son has a slightly misshapen head on his left side. Everywhere else is perfectly round. His dr noticed it last month at his 6 month appointment. He sits up and is on his tummy all the time except for naps and bed time. I think the indent is caused by my arm while I’m nursing, because he really only nurses on my right side due to my left side never being able to fill him up. He has his 9 month appointment in December and I need some ideas on how to help round it out before then. We alternated sides of his bed and he still goes to his left more then his right. He’s able to turn his head to the right, however I do thing there is some tightness in his neck. Would going to a chiropractor be beneficial? His dr said the possibility of him needing a helmet is really low, due to how mild it, but she does want it to be rounder by his next appointment. Should I hold him differently? And how? This is causing so much stress on my end, because I thought I saw it making progress and now I feel like it’s not, but I don’t know if that’s just me being paranoid. Any advice would be wonderful. Thank you so much in advance.