I main LB, and the following champs give me a headache:
Each of them either has a lot of sustain, long range, point-and-click CC, or a way to interrupt my combo with shields or untargettable abilities. For example, Liss can stop you dead in your tracks instantly with frost nova or her ult. If syndra manages to stun LB at any point, she can flash in and press R and LB will just melt because LB is squishier than tissue paper. Annie can insta-cast tibbers and burst you down immediately. If LB doesn't get a kill early on, these matchups get worse and worse over the course of the game as they also scale better than LB and are more useful in teamfights.
When you're in a weak lane that you think you can't possibly win, focus on getting CS without taking harass and immediately spam ping as soon as they go mia. Following LB is usually a bad idea because she can sit in a bush and wait for you, so push hard. If you get negatron and catalyst as your first items, she can't get fed off you, and if your other lanes keep safe, it will turn into a 4v5 late game, while you can build a roa and abyssal and almost never die to her.
It actually doesn't take a whole lot of resists/hp to outtrade her - once LB loses trades and takes more % of her dmg than you do, the lane is won and you have a very good chance of winning the game. Don't be afraid of her and fight back if she harasses you and plays aggro.
It might sound trollish, but Janna Mid actually wrecks her harder than any other champ. If you really are struggling and want a go-to champ to deal with her, Janna's your pick. Max W and interrupt all her dashes with your tornado, and shield her combo, and she literally can't do a single thing. Late game you become a pushing machine, and LB will fail to do anything to your team because you're Janna.
