Thanks for the feedback! I'm glad you've enjoyed it.
The level-ups for sexual stats are still not implemented, but will be coming in the next update or two.
Pregnancy will be added to the game later for Rena, Annestria, and the female MC. I'm not sure about Valerie since succubi in Rebel Duet get pregnant in a different (non-sexual) way. But I can consider including pregnancy content for Valerie as well if it is requested enough.