I feel so upset

Ki
Elliott is my first born and my last. I don’t know what’s normal and what’s not. I’m just so exhausted. Elliott has an incredibly detrimental attachment to JUST mom and dad. No one else can watch him. Every mom I talk to says this isn’t normal behavior. He screams bloody murder when even his grandmothers try to watch him. I feel so lost, I don’t know what’s wrong with my sweet baby. He will be 6 months next week. We try to take him out as much as possible but if a stranger even looks at him, he just loses it. I asked his pediatrician about it, seeing as this begun before this “normal stage” of knowing the difference between strangers and not and he just said that it’s so early for Elliott to go through this and maybe he is just “intuitive” for his age. Please- has any other mom gone through this? I’ve posted about this before and just gotten rude comments about comforting my son which I obviously do but I don’t feel that his attachment is healthy at this point... I can’t even leave a room and I’m a working mother. It’s so much guilt and nothing I’m trying seems to work. I would love some wisdom or encouragement, anything. I’m on the brink of tears. I just worked a 12 hour shift and Elliott’s father has been out of town and he just screamed at his grandma for almost the entire time.
Thank you.