I hear you! I feel so unsexy all the time. I'm planning on buying myself some really nice lingere as soon as i drop the baby weight to make myself feel better again.
I cant exactly relate to the pregnancy photos, I lack the self confidence to take nude photos regardless of being pregnant or not. But most people get nude photos touched up, not only pregnant women. Look at all those celebs you think none of them got stretch marks? Photoshop FTW!!!!
I think its great that you want to get them done, and if you don't do it you will regret it I'm sure. If you end up hating them, stick them in a locked box and put them away in the back of the closet. I'm sure In 30 years you'll think you look amazing!