20 credits isn't too many is it?

I registered for next semester's classes yesterday and got everything I wanted. The two compsci classes I need are Data Structures & Analysis and Computer Organization, which look pretty interesting. For my other electives I over-registered again. By this I mean I registered for 3 more, which puts me at 20 credits and I may drop one of them like I did this semester. I registered for Managerial Economics and Managerial Finance, which are the follow-ups to the economics and accounting classes I'm currently taking. Four economics classes total or four finance classes would each give me a minor. I'm enjoying learning about money and the economy and I think I'll try to talk to an advisor from the Management department to see if there is any way I can work some of these classes together into an interdisciplinary dual major. The fifth class I registered for is Intro to Philosophy of Science, which looks fairly interesting and fills my communications-intensive humanities requirement. I hope I can handle taking all 5.