At my university you could only study one major + one minor during undergrad studies, and only one major + additional courses to "broaden your horizon" during graduate studies. I'd have loved to study more different topics, although I wouldn't have been able to finish my studies so soon.
For self-defence my general advice would be to practice some simple things that suit your body type, because there's no "magic move" for everyone and for every situation. Observe your surroundings and the people around you to evade critical situations before you really have to defend yourself (trust you gut feelings, so to say). And if you practice some self defence stuff, try to do it as realistic as possible - just to get to know the feeling of being attacked and having to do
something. Personally, if it was neccessary I'd go for a mix of screaming, elbows and knees and attacks to the head/neck if possible.
I have to add that luckily I've never been in a situation yet where I would have needed any self defence for real.