What does interesting mean to you?
Girls are NEVER uninteresting, it's you, just out of shape.
NEVER blame anyone else than YOURSELF.
Think about a conversation you really enjoyed.
Did you lead it?
What did you talk about?
Could you talk about the same topic with someone else?
Does the topic lift YOUR mood? (I usually don't think what others think of my stuff.)
What could you throw in to improve it all? Playfulness? Boldness? Aloofness? Bragginess? Leading more maybe? Doing something a little weird but hypnotic to both of you or just yourself (staring in her eyes noticeably, touching her repeatedly and noticably, etc.)?
Do your conversations hold emotion? Emotion is the MAIN thing a deep conversation should be built upon. (You can try emotional meditation, which is, just get a chilled/emotional song and watch what feelings appear, just WATCH them, know you HAVE them but do NOTHING with or about them.)
SONG.
http://www.youtube.com/watch?feature=pl ... 30ecKr96Hw
After you know what you feel, just know if you want to express it, stop caring what anyone thinks and just BLOW IT ALL OUT. Fun, deepness, sadness, girls love emotions, all of them, even anger is good sometimes when it's aproppriate.
What do YOU want to talk about?
What do YOU want to tell her?
What do YOU want?
You want sex and you think you can't talk to her about that?
Pick the next best topic for yourself.
If that doesn't help, I suggest doing some crazy stuff, watching movies, surfing the web or anything else that would increase your knowledge about everything, so you'd REALLY have shit to talk about.