Only the Jenna route is still in development, the others are basically finished. The creators has said that there won't be a complete/true story, at least not in Echo, since they have plans for a direct sequel (Arches) that follows on from Flynn's route - but they've also said that all the routes are considered canon so I don't know how that will work.
In the meantime you can play The Smoke Room for more information and lore. It gives you quite a lot of details which you can use to piece together the mystery.
Also, you actually don't get to chose being bi or not, not really. If you chose gay, Chase will say that he doesn't feel like explaining his sexuality and that saying anything else confuses people, implying that he is still bi but just chooses not to say it. This is one of the reasons I love Echo so much: unlike most other VNs, you are not Chase, Chase is his own person with his own past and ideals. All you are doing is influencing Chase's decisions, not making them for him.