Wow, this is all really interesting. I come from an atheist upbringing and became a Christian about 7 years ago. In those 7 years I have had some bleak times when I wasn't sure if God really was there or loved me. I've also had some brilliant times when I felt that I knew God was definitely there, with me, and loving me.
I guess one of the best things someone taught me is that you can't rely on your feelings. Feelings depend on all sorts of thigns - whether your physical needs have been met, the conversations you've had during the day, the weather, lots of things.
For me it was about deciding whether I thought this person called Jesus existed as a real person in history, and if so, whether he was God or not. Once I decided I did think it was true, the feelings followed.
That's not to say its been all easy, but throughout I knew why I had decided to follow Christ, and could fall back on this when the feelings lapsed for a while.
If you would like a Christian perspective, I would also recommend Ship of Fools. You could also try looking in the Bible at the psalms, a lot of them deal with struggling with faith or feeling down.
I hope you find your answers, whatever you conclude.
Michaela