Hey! I am a senior. I have taken AP language, literature, biology, chemistry, government, and world history. Overall, they are quite difficult classes, however, if you put forth the effort and pay attention you will be fine! Do not over-stress yourself about it. If it helps, I have not gotten a grade lower than a B in any of the classes! You'll do great. (:
I am currently taking 5, and I took 3 last year. I plan to take 4 senior year. The key is finding out about the teachers who teach the classes ahead of time, and balancing easy/moderate to difficult AP classes.
Most 11th and 12th graders (depending on ur goals, of course) take 3-5 AP courses if they want to demonstrate academic rigour for university. If you want to challenge yourself, I would take any number in that range.
Explanation:
Don't be nervous. You should also confer with school counselors and profs. Older students might also give you advice about teachers you may end up with. Good luck!