A little background: My parents divorced when I was 10. Dad had a vasectomy and mom got pregnant again and I guess I blamed my half-sister on the divorce and we used to fight all the time. When I was 18 and joined the Navy I grew up quickly and on my first leave back I promised sis I wouldn't yell at her again. She is a super sweet kid and I feel crappy for the way I treated her and I know that if I had an older brother who treated me the way I treated her, I wouldn't have a thing to do with her, but she still looks at me like a rock star.
So here's the dream: I'm aboard ship about to finish duty and all I want to do is get back to quarters and get some sleep. But as soon as I think I'm finished and I start to quarters I remember something else I'm supposed to do and I do that. Then I head back to quarters and remember something else I have to do. This keeps going on again and again until I'm finally walking into quarters and I see sis on my bunk and I start screaming "GET OUT OF HERE!" She starts crying and I says I promised not to yell at her again. I keep screaming and tell her I don't care what I promised and tell her that I'm not getting in trouble because of her and for her to get out. That's when I wake up. I wake up furious and then I feel guilty and like a first class jerk. I've had this dream six or seven times in the past month or so and I feel like scum every time.
I made a lot of mistakes growing up and I treated those who cared about me the most pretty bad, and there's a lot I'm not proud of, and the way I treated sis is at the top of the list. Why do I have this dream and what does it mean?
When we dream, often our brain is sorting things out. When we have a recurring dream, the underlying emotion or event is still present, so your brain keeps trying to deal with it. This is why your dream is recurring.
The interpretation seems obvious to me. In fact your brain is setting it up for you. Your dream is broken into two halves but it's still the same dream and the same problem. So your brain is giving you a literal manifestation of the problem, in a concrete easy to recognize form, and then shifts to a somewhat symbolic treatment of the problem.
The first part of your dream is pretty straightforward. In the dream you are sea duty and you are performing your daily duty. Duty, duty,. Duty is extremely important in the military and they hone a sense of duty, and everything must be subordinate to your duty. And here you are tired and wanting sleep, but duty comes first. You need sleep, but sleep has to be subordinate to your duty. You can't say "I'll take care of that tomorrow. I'm going to bed now."
Then when you get to quarters, your duty is performed and you can get to sleep, you can't sleep because your sister is in your bunk, and you get angry and tell her to get out. This hurts her feelings and you continue to yell.
So part of it, as someone else has suggested is unresolved feelings of conflict between your sister, the lingering guilt you haven't been able to shed. What else is there? You have wake up and you are angry so there is real anger there. You feel guilty because in your dream you are yelling at your sister and so you think that she is the cause of your anger. That's why the dream doesn't make sense to you. You're not angry with your sister, so why would you yell at her?
I bet you were angry when your parents got divorced. Instead of dealing with the cause of your anger, your mother's infidelity, you took it out on your sister, the product of the infidelity and totally innocent, so you blamed her for the divorce.
So here again your sister bears the brunt of your anger, when you are not angry at her. So what are you angry about? Your dream gives you the answer. Your sense of duty is keeping you from sleep, and then when you get a chance to sleep a family member is occupying that space. It might just be as simple as you are feeling more homesick than normal and you're angry that you can't get home as often as you would like.
I don't mean to suggest that you are unhappy about your service in general, but no matter how much we like our job, there are aspects of it that we wish were different and things we would rather not do. But it's clear that, in some respects, you are angry at the situation that is keeping you from your duty.
It sounds like you're still working through the guilt you feel at the way you used to treat her. Perhaps if you put your feelings into a letter to her, it will allow you to both apologize and let her know how great you think she is now. She'll probably treasure a letter like that from her older brother and she'll try to live up to your good opinion of her.