I'm so happy you enjoyed it -- a big relief actually. I've never written mpreg, and I don't read it, so I'm completely unfamiliar with the trope and was afraid I'd ruin whatever aspect it was that people enjoy about mpreg.
Harry wasn't really pregnant. It was a scheme cooked up by Madam Pomfrey and the potion she gave him enabled him to mimic the physical and emotional aspects of being pregnant. And yeah, the dog roleplay was weird to write; it was as close as I could get to including creature!fic. (I really did try to hit all your kinks. :D)