I can tell you by my own personal experience in pharmacy and med school, that it is always a big transition entering a graduate or professional school. The upside is that it will get better! I can't think of anyone in my pharmacy class or med school class who didn't have varying degrees of the feelings you express.
The first semester is not always the hardest per se, but it may be the worst. Basically, you are entering a professional school and now have to adapt to new teaching styles and tons more information. The material will only get harder and increase in volume, but you will be used to it! In a couple of months, you will still think pharmacy school's material is difficult, but you will be used to it and better able to handle it.
I went through the same feelings when I started pharmacy school. I find medical school (much) more difficult than I found pharmacy school, and the amount of material is much, MUCH greater, but I actually have had an easier time adjusting than I did when I started pharmacy school! Moral of the story, the material will not get any easier, but you will grow and get used to the volume and difficulty of material.
It's only going to get better!
Jason