I don't know how highschool system is in your country though I hope you're not stressing yourself for the exam and such,ahah you found the right person to discuss university with~I always talk in front of newbies who visits our university from outside and everyone is the same like so dont worry about what you feel right now~
The way to decide which course of the university you'll take is by visiting universities and attending their speech~Though this up to your school,do they make trips for visiting university and such~?