Well, from all I have read, Steam offers your best chance at realizing a lucrative payday from your efforts. I think your game is worth $15 or more and I think the majority of players would feel the same. I'm sure that most of your subscribers would understand making changes to the terms, especially when you explain your reasons. You've always been prompt with updates and dev reports and that generates a lot of goodwill.
If you don't make money from the game, there's little chance for a second (or third or fourth) game, and I believe that most players, especially the type that buys into Subscribestar and early access games, want to see their favorite creators make additional works in the future.
My favorite example is Eternum, which I think is one of the finest adult games around. His previous work was good, but Caribdis truly came into his own with Eternum.
Then there is Mundo Games with Above the Clouds; it's a great game, but after the release of the first season on Steam, he seems to have gone silent, even on his Patreon. Did he see a big payday and lose interest in the second season? Or was he disappointed with the sales and decide that it was not possible to continue the project? I don't know...
Whatever happens, your core fans will support you. You may lose some along the way as you navigate the road ahead, but most will remain true. It's the larger pool of consumers of adult games that you really have to worry about, who will make it a success or failure, and Steam is likely the best way to get your game noticed by that group.
Anyway, I do hope it works out for you, and that you make mad amounts of money in the end. I really want to see a future project!