Can our relationship survive summer break if we haven't had sex yet?

I am a 19-year-old college student and am seriously involved with my boyfriend who is a 20-year-old college student. We have even talked of getting married someday. Our relationship is very close and we talk about everything, and he is very wonderful and supportive. I feel very committed to him and would really like to have sex with him. We have tried twice, but it hasn't really worked out because my vagina is too tight. I am pretty sure the problem is just that it needs to be stretched more, because I have been to the gynecologist and don't have any infections. He says that he is okay with whatever we do and that he loves me no matter what, but I still feel guilty about not being able to go all the way. How do I get over this guilt? I will be leaving college for the summer soon and we will be separated for awhile and I want to make sure that our relationship is as solid as possible before I leave so we have the absolute best chances of surviving the summer!