I have just finished watching the movie for the 2nd time back to back and i think the whole movie is Clare Abshire's story who is also a time traveller trying to save her unborn child using Henry who never knows that his wife can also travel through time and can actually control her traveling habit better then Henry like their doughtier. I also beleave that Clare Abshire's mom and sister also have this ability and their father is aware of it(Remember the first conversion between Henry and Clare Abshire's father).If you start to see the movie again assuming this all the puzzles are kinda solved. I think what im trying to say is when Clare meets Henry in the library and told Henry that she knew him from childhood,
She is actually trying to sent Henry to that moment in time so that Henry can fall in love with her younger self which will lead to marriage and a baby, whose life she was actually trying to save in the very first place. Please dont flame me....I might be worng but just think isnt it a little wired for a 7year old saying "there is no such thing as time travel" and besides she was way mature both the times she talked to Henry.