Hmm, did you do that Police Station quest? I gave the guy the signal booster, but didn't choose to join the BoS. Haven't seen any of them yet, maybe they come later.
Hardest fight I had was more difficult because of the terrain than the enemies themselves. Some weird settlement with Supermutants, took out the grunts no problem. But in one watchtower was a Skull level Brute with a crazy powerful Lazer Rifle, and over on a hill to the left was a Legendary Brute with a Minigun. There was no way to fight one without the other having you in their sights. Took for-goddamned-ever but finally found a spot to get potshots on laser boy, then played PeekaBoo with the Minigun guy. He dropped a Lucky Minigun, which is cool I guess. I don't know if Followers can do critical hits, but I gave it to her anyway.
Mirelurks were kicking my ass early game though. So fast.