Wedding Ring

Hello. I want to ask my girlfriend to marry me. I really love her and in january we discovered that she is pregnant.We are so happy, but I know she's upset cause it's not what we wanted for right now. She always dreamed with a beauty wedding and I really want to make her happy. A wedding ring is just a part of this.I'm undergraduate and work in a store. I pay my college and I help my mother in home.Beyond my girlfriends dreams come true, I still want be a perfect father. I didn't have a dad so I'm working hard to make some money to my son.A wedding ring is too expensive here, I won't buy that one. Just a cheap, anyway I need help.Thanks  Love