maternity photo ideas?

So my baby bump is big enough to shoot maternity photos, unfortunately the small town in which I live in has two photography studios, both of which are outrageous in their prices. So my sister who is a pro with a camera offered to do our photos for my fiancé and I, only problem is I have no ideas what so ever. Does anyone know any great poses or shots to take? Id like to do a few gender reveals since we haven't announced the gender. I'd also like to incorporate something relating to a rainbow baby, since baby Anderson is a rainbow baby. Ideas and thoughts would be much appreciated and helpful 😀