She has proposed to me, what do I do?

I have a girlfriend, who is two years older than me, but loves me so much. Every night before she goes to bed, she calls and wishes me a good night.

I am still a student, while my girlfriend is working. 

My girlfriend is pestering me to marry her. She says she is getting old and that is why we need to get married now. I would like to complete my studies before I get into marriage.

What should I do?

Gonza