My Age?

Hello All!
This child raising thing is quite difficult/frustrating. I told Tobias that I refuse to have children until I am well into my thirties. That gives me more than ten years because...I am only twenty. 
*audience gasps*
Yes, I am twenty. Am I young? Certainly 
I feel really scared sometimes of course.. I don't know what I have gotten myself into. But I do know that I have been with my fiancé for four years and there are many people who have married and had previously known each other for less time than that.
I have his help, he is older than me and has been doing this whole "adult thing" for quite some time now. 


Next year I will be going to university (again), somewhere in Germany, and I need to know my career path immediately. I'm not so sure about this. Every since high school I thought I wanted a career in international relations. I know Swedish and English by birth and I have learned and can now speak Russian and German fluently. International relations sounds like the perfect career path and is still what I feel passionate about. I made good grades all through high school and my one year at Georgetown but I always focused on the humanities. 
Recently I have been doing lots of reading on the profession of gynaecology, it is so random.
I have always hated the sciences, but I really feel strongly about this and could see myself having a more rewarding life by helping women in this way. 
Reasons?
I have always known these facts but the statistics still alarmed me when I read this article .

Also, I know from personal experience the contraceptive access in American for teenage girls is extremely restricted in comparison to many European countries... and there are a lot reasons for this which I could go into but probably wont.


In short, this is something I am seriously considering. Tobias who is also going into the health field was really excited when I told him. Luckily I have (sort of) a year to think about it. 
Hopefully some older and wiser folks can give me their opinion?