Shame, sounds like you've really been struggling with this for a long time!
My initial thought was that you should try Tea Tree Oil, but I see you already did that. Did it seem to help at all?
I did a quick google for home remedies and found these two sites that offer helpful suggestions:
voices.yahoo.com/5-home-remedies-nail-fu...11973353.html?cat=68
www.toenailfungustreatment.info/most-popular-home-treatments/
I think the second one actually sounds better personally.
Maybe try tea tree oil again, without the vinegar this time, just drop some tea tree oil onto the nail and maybe massage it in, and then add some coconut oil which will help to moisturise the area, but also contains anti-fungal properties.
I really hope this problem resolves itself soon.