Hi there, I really need some advice and don't know anyone else who might understand my situation. Sorry if this is a bit long, but it's a very complex situation that really messed up my life recently. There's a TL;DR at the end if you don't want to go into details.
So in case some of you don't know, I'm a soldier. I'm 21 and live with my family, and my older sister is a university student that comes back home from uni almost every weekend (during the week she lives in an apartment next to where she studies).
I usually don't really get to play during the week, so when I'm home on the weekends I try to practice as much as I can. Even though I can't play regularly, piano is still a huge part of my life, and it's sort of the only thing I like to do when I'm home, and I really look forward to it.
The thing is, my playing kind of annoys my family. They're mostly not music enthusiasts, and they don't like the noise. If it were up to me, I'd play all day long when I'm home, but I know it can make the upset if I play too much, so I try to be considerate. In order not to interrupt them too much, I usually play sometime from 10 AM to 1:30 PM, and from 5 PM to 7:30 PM. I don't play the complete time (again, in order to be considerate), usually I play 2-2.5 hours a day. Like I said, because I mostly get to play during the weekend, this means I only get to play a very limited time each week. It makes it very hard to progress, but because piano is the only hobby I have in my life outside the army, I treasure these few hours each week.
So this was the situation until a few months ago, but recently my older sister started complaining about my playing because she says it interferes with her studies. At first I just played less in order to keep her happy. I changed my playing schedule, played fewer hours, etc, just to keep her happy. But over time I realized this isn't enough for her - she wants me to stop completely whenever she wants to study the whole day. I won't go into details, but this opened a really huge fight in my family, because (naturally) I'm not going to let her or anybody else take away the only piece of personality I still have left outside the army. I have so little time to play each week, and I don't want anybody to take that away. Also, she can study all week long and she has a place of her own. But because I'm generally a more considerate and flexible person than she (she's not afraid to throw tantrums when she doesn't get what she wants), my family is really pressuring me to gradually give up more and more of my time, even though I try to explain how much piano means to me.
Did anyone else here come across a similar situation? I really don't know what to do. I already struggle with the fact that I don't get to play that much, there's no way that I can give up more of my plkaying time, not to mention giving up piano all together. I can sometimes go to a local conservatoire to practice, but this is hardly a real permanent solution.
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TL;DR:
I'm a soldier that can only play a few hours each weekend (and that's about it) and my family is pressuring me to gradually play less and less because it interferes with their lives. I can't make them understand what piano means to me and because I'm sort of a pushover I constantly find myself giving up on piano more and more. What can I do?
If you had the patience to read this, thanks a lot in advance!

Gilad