Congratulations on the little one!
we had no issues with the click in rear facer in the middle, but when we had to get the next size we had to get 2 seats. the first one was WAY too big to fit in the back, even though it was supposed to be a compact seat. We now have a maxi cosi pria 70. We coulndt get it to install via the lap belt so we took it to the local car seat installer. They also couldnt get it to fit correctly, the shoulder belt clocked the seat to the side; so we have to use the Latch system behind the passenger seat which eats up some front leg room.