Yo, although I wrote the novel itself in 2 weeks, I consider that as 10% of the work being done - I'm at my best during the editing phase. That's why I was so quick with the first draft - which, for me, is basically a list of cool ideas and characters linked together with unconvincing dialogue. I wanted it out of the way quickly so I could sit down with a big pile of paper and a nice red pen over Christmas, polishing up the writing until it shines. That, for me, is the real pleasure of writing.
FWIW I wrote 10k a day on Sundays, and 5-6k a day on workdays. I spent all day at work dreaming about the story, letting it grow in my head, so I don't think it's rushed, so much as hauled out of my head before I had time to think about it too much and get carried away with thoughts of self-doubt.
I shall take the advice of the comments so far though, and bung in another 30k words somewhere. I've got a feeling that the falling in love (cheeeeeeeez) isn't so convincing, so maybe I could do something there. 40k looked a bit thin. You know how with some books, when you think about them, you sum them up by thinking of a typical scene that may not actually be in them? For example, 'Salem's Lot by Stephen King would conjure up images of Ben and Susan talking in a back garden, or Name of the Rose by Umberto Eco would be a bunch of monks eating dinner during a dusky, far-off night? Well, I don't think my book has any 'archetypical scenes.' It just goes from situation to situation, which are all quite different. Maybe I need to bring that in somwhere.
Apologies for the tangent-filled post! This is what happens when your fingers are itching for a keyboard and you've been stuck washing pots all day in a sandwhich shop
Hmmmmmmmmmmmm.
