They are almost caught up to the source. The LN started in 2012, and if my understanding is correct they have not even introduced the third slave yet (In the case where this is the manga that started in 2017). If this is getting a second season it won't be for a good 4-5 years.
From my perspective I am fine with this series not getting a second season. I have nothing against tasteful ecchi and hentai but making a harem out of slaves is outside of my comfort zone, even if they do consent. I also like my characters to be consistent. Constantly changing proportions is a pretty big turn off for me. Lastly, the plot was not good enough to keep me interested.