Can’t get more settlers

This is my first time doing a play through where I actually try building up my settlements. The problem I’m having is no matter what I can’t seem to attract any more settlers. I have 12 at Sanctuary which half of them are companions that I just sent there so I know where they are. I have plenty of water, power, food, defenses, and beds, and happiness level is at 76%. Ive started working on abernathy farms (5 settlers) and the castle too (5 settlers). All of them have recruitment radio becons, but my settler number just doesn’t grow. I also have my charisma maxed out. Idk why my numbers aren’t budging. I need more settlers so I can assign them to jobs and supply lines.