Let's be blunt: You're 20, which basically means you're just barely not a child anymore, you have your whole life still ahead of you, and the "I am 90% sure" is just another way of saying "I think I wanna do it, but I don't know".

What if you start getting into Game Design - there are countless threads on how to get started in here, but my favourite one is this - see if you like it and then make an informed decision for yourself?

Chances are people will have vastly different experiences to what you will encounter anyway since, while game development is a global market, working conditions still greatly depend on where you actually exercise it.

I don't mean to be a party pooper, but working in gamedev can be completely shit up to really awesome. It takes a great amount of skill and luck to be part of the latter!

But the cool thing is, no one really cares if you got your degree at 21, 23 or 28. If you're skilled and can do the job reliably for the right money, people will hire you.

So, chill, learn the craft, and get going :)