its totally understandable to be feeling lonely because naturally you're going to miss the time you normally spend with him. The whole "needing space" its natural and well relationships are compromises right? Soo its just something you're going to have to deal with.
even if you dont see him, maybe it'll set you at ease more if say he called you at night and you guys talked a little and said goodnight? You're physically seeing him but it gives you that reassurance thats he's still there for you etc. I dont think asking him for a few minutes out of his day just to say goodnight and see how everythings been is asking for too much. Esp. if you guys been together for so long.
Also during the day i would just say distract yourself from thinking about him too much. Its just gonna make you feel more sad and miss him more. Go out with your friends or do w/e that you enjoy. Hope that helps. Being a girl too i know exactly how you feel. And im kinda going through the same thing with my bf except he's far away...
so dont think too much about! thinking and fretting over it will just make you feel worse.