baby with separation anxiety?? HELP

Hey ladies so my LO is almost 9 months and breast feed and also takes bottle but does not take formula he refuses it. It seems he has separation anxiety and he cries a lot because he also fights his sleep but it seems he doesn't get tired of cryin and sleeps. I've read that if the child has separation anxiety he will put his head on the parents chest which he does to me.  has anyone had this problem how do u fix something like this. I hate to think I might have caused it by carryin him to much or breastfeeding him I feel horrible for something I really shouldn't cuz as a 1st time mom I'm only doin what I thought was best for him ?