I don't think your are obsessive at all!! I know loads of the girls on here are taking progressive shots, it will be a great record.

My DH has taken loads of me. We are currently building a house so as we are taking progressive shots of the house, I am standing in the photo and he takes shots of me! So as I am growing the house has been growing too!

I have been keeping a journal as well, just detailing how much I have grown, what the bubs is up to. Lots of my g/f's say that they tend to forget stuff like that, so you'll be glad you've made the effort now.