Sounds like you need to unlock Amber. You'll need to progress with your photography until your weekly income is around $45-50 IIRC and then she'll send you an email. If you haven't started at all, you can get your camera from Katie on Monday evening. Then you'll need to do 2 photoshoots with Katie on Sunday evenings to unlock photoshoots with the other girls. Most of the shoots happen where you normally find the girls but a couple you need to invite them over to your house (check phone by the pool) and there are a couple outfits you have to buy to unlock shoots. Finally, don't forget to post the photos to your portfolio on the computer in your bedroom or you won't get the next shoot with that girl.