Today I wrote a letter to our baby

I'm planning on writing a letter every year around bub's birthday and then collating them all along with my favourite photos of them that year, and putting them into a book for him/her to read when he/she is older. I'll also do one once our baby is born with our birth story etc and maybe another when bub is around 6 months old. It will be nice to look back and see what bub's personality was like at each age, what their interests were, their likes and dislikes, milestones they reached etc.
What I need help with is how to make this into a book? Where can I get this done? Is there somewhere I can get a few pages done at a a time and then save them to collate later? I'm imagining a two page spread for each entry or maybe longer if my letter is too long. For my first letter I'd like to have the baby's ultrasound photos as well as some of my maternity photos so bub can see what I looked like when I was pregnant with them. Then for my birth story - photos of them in the first few days of being born etc.
Does anyone have any ideas?