Relationship help!! ?

Ok so dont worry my girl and i use the same yahoo answers login. Anyways im 20 (male) and my gurl is 19. We wanted to wait to have sex because we wanted to wait untill the right time. Well i told her it would be a suprise when im ready. She said okay. Well im planning on getting engaged to her we have been datin four years. And i dont know how to really ask her if she wants to have sex. not only but im nervous about getting condoms because its like everywhere i go i see some one at a store and they will see them. Also i dont want planned parenthood condoms. So any sugestions on how to ask her to have sex and how to get condoms? also please be respectful i dont need anyones bs.