Oof. Sad you didn't like it. The progression of the game is slow because there's 10 sizes planned for Iris, but only 5 in this release for the Game Jam, so I unfortunately had to make it hard to get her bigger. Additionally, you'll notice you unlock flashing, nudity, then blowjob per size - the final release will also have 3 more sex scenes per size, so you're rewarded more for your grind.
That said I just pushed a patch to decrease the cost to upgrade Iris, make the game a bit easier, and fixed the touchscreen issue for Android users.
Thanks for your feedback, hopefully the patch will make it more enjoyable for others, and I'll work to think of ways to make it less of a grind.