British Literature-this is the standard class because I am not very good at writing so I am definitely taking this
Precalc Honors
Spanish 3
AP Gov+AP Econ
Physics-every junior is required to take this
I have another block where I can double up on science or do two electives.What class should I do to make my schedule better?
Take some honors science so you can take the ap senior year.
What are your interests? Intended major? If science is, then double up on science. If history is then take another history, etc. Make sure you take great classes, but that they interest you as well. Have you considered AP Bio or AP Chem?
What type of colleges are you aiming for?
The answer will affect what we suggest 
In addition, do you live in a State where college admissions (public) are linked to rank in class, and if so will certain choices affect your rank, placing you in/out of contention for some universities?