Hello jenshoe and welcome to a2k
Hm, it looks to me that your boyfriend was overwhelmed with raising his two
little kids alone, and when you came along, the arrangement of living together and you taking care of the girls, seemed to suit his needs.
Perhaps he is looking only for someone to help him raise his children, as he doesn't seem to be interested in your children, nor is he allowing them to have a picture of their father in the house - which is ridiculous to deny your children what his children are allowed to display.
Obviously, you and your boyfriend want different things in life, and after
you have had a heart to heart talk with him (as Phoenix suggested),
you probably will know more what the future holds in store for you. It is up to you to decide then if you can live with him as his "house keeper" with fringe benefits, or if you and your children deserve better.