Hey...don't dig yourself down in depression, don't go around feeling too jealous, just accept the fact that you are in the army, and don't let them break you down. Yes, it sucks that only men do military service (maybe not in Israel), but just try to accept that fact, don't start hating yourself for being born as a man, just think about what could have happened to you if you were born as a woman in one of those countries where they mutilate girl's genitals and force them to cover themselves totally when they are outside of their homes.
What ever you do, don't fall into depression, it will only create loneliness and nothing else. At least you can spend the weekends with your girlfriend, you could maybe ask her for some support, maybe she can take you with her on fun activities and introduce you to new people.
One day, it'll all be over, it's not like you are in the army forever.
Take care.