Hi Sandra;
Clearly, they love your work and are interested enough to contact you for additional details. Unless you have some new information that you might share with them, I would give them the space to continue their processing of the idea of buying.
What has just occurred is to send them one of the images they are interested in, in situ above a sofa or bedroom which could help them visualise it in their home. Some people need that additional boost.
Good Luck! Your images are serene.
Anahata Ishaya
NZ