I did 5 (albeit all maths/science subjects), alongside an EPQ, AEA and STEP... it's manageable for sure, but come exam season, you will probably have to start revising a lot earlier than others. Surely you would self-study at least one of them -- if so, which?
Remember that enjoying a subject and studying it at A-level are not necessarily the same thing. What's stopping you from reading about geography in your spare time - do you need to take an A-level in it? Because it can quickly become an unwanted distraction for your other studies/exams.