without following you from the beginning it is hard to say what happen.
from quick observation it is normal your competition rose, the new airport he has 1300 slot in it, while you only have 500 in it. Your competition is also deploying a much larger aircraft size recently on some large demand route.
for your loss I can only assume you operated at one of the close airport. Or demand has been shuffled since the airport opened. check your route and see if any of them is not running.
A drop in LF in LH is normal due to airport switch, it will go back up very soon.