Racheal got pregnant about 1 month before Monica and Chandlers wedding. Their wedding was on May 15th, Making racheal almost 1 month pregnant at that time. In the episode: The one with the creepy holiday card, it says Racheal is 4 months pregnant. That isn't possible... It is at least december in that episode, making Racheal at least 8 months pregnant. am i right?
You are forgetting about the summer break. The first episode of the season 8 took place on the same day as the last episode of season 7, even though it was months later in real life.