My question for the OP is how old are YOU?
What your parents say shouldn't carry so much weight that they stop you from being happy.
Life happens in medical school. Marriage should be about you and her. You should have a need to be with her. So if these long phone calls at night are a bother, then don't get married. If you have to talk everynight or you feel like you'd die, then propose.
One final thought from the great Pink Floyd:
"...to martyr yourself to causion is not going to help at all...because there'll be no safety in residency [numbers] when the right one walks out of the door..."
As for me, I'm 27, been married 4.5 years. I'm a nontrad, was a nurse prior to medical school. I was disowned by my family for a time for marrying a 'brown boy', but I'm so happy to be married to him I couldn't imagine life without him.
The only problem we really have is that we have to go so much out of our way just to make time for the other person since we're so far apart. If we were living together, a lot of that tension would be removed. She has explicitly said that time we would just spend in each other's presence daily would make her happy. So if we're living together, eating together, and at the end of the day, doing a bit of laughing and joking together, etc., that oughta cover it. It's just that right now, she feels like she has no place in my daily schedule because I've always been either cramming for an exam or studying for the MCAT or filling out applications. In reality, I haven't had much of a social life at all, so it's not like I'm specifically ignoring her. But whereas I bump into other people from time to time around campus, I have to make a concerted effort to make any time for her (because, again, she's far away). And if I do give her the time she needs, I begin looking unnatural to people around me; there are some days when my friends around me are like, "Man, you're on the phone a lot" or "Man, you text a lot on your phone". I just want to end all this covert keeping-in-touch, and just be able to walk around with her and be like "How y'all doin, this is my wife" and I can just handle my business in peace. So, basically, I think marriage would relieve the majority of this problem.
I know what you mean about being disowned by your family. I have a friend who's been disowned by his family for marrying a girl of a different culture (even though they're the exact same religion, which you'd think would be more important to the parents). I come from one of those cultures where, for some stupid reason, it is unheard of for a male to get married before receiving his doctorate degree and, for most families, it is unheard of for a female to remain single past the age of 22. End result: arranged marriages between teenage girls and grown adult men where the two don't even know each other. So my family is saying to me "don't even think about marriage until you get your MD, or better yet, until you start residency", while HER parents are telling her "you're almost freakin' 23, all your friends are already married, what's the holdup?!!" And she's been fighting off suitors for about 5 years now... yes, that means her first one arrived when she was 17.
However, regarding the possibility of me becoming a "black sheep" for marrying too soon, there is one stupid aspect of my culture which can come in very handy for me: There is no such thing as a "black sheep in medical school." With my acceptance to med school, I've basically been granted immunity from ever becoming a black sheep, no matter what I do. It's a stupid part of our culture, but hey, I'll take it.
(As an aside, I actually didn't want to become a doctor at first because of how ridiculously highly-touted they are in my community, but then later on when I shadowed a doctor and enjoyed the experience so much, I decided to pursue medicine IN SPITE of my culture.)