I see the author still replying to comments semi-regularly, so I'd like to make this appeal:
Please continue the development of this game.
Games of this kind tend to be less games and more interactive fetish content. Any gameplay they have is simple at best, and practically vestigial at worst. Seeing a game that actually integrates the fetish content into gameplay refreshing and disappointingly rare.
What isn't rare among such games is an abortive development. Good or bad, the more ambitious ones usually seem to fizzle out after a few updates. I see signs that this game could be headed in the same direction, and that's a shame given the potential it has.
It's going to take a lot of development, content additions, and tweaks to become a finished product, and let's face it, it's not going to be the next Undertale if only because of its subject matter, but the fundamentals are solid. All it needs to succeed is the one thing these kinds of games rarely get: a long term commitment from its developer.
As for specific suggestions, like I said the fundamentals are solid. What the game needs more than anything is more content.
One big change I would make is thus: upon completing a level, Erith loses all the weight she gained, but she retains her skills (base HP, FD, DMG, DEF, etc). Furthermore, add a stamina bar. At base weight, Erith can move as much as she wants without draining stamina. At higher weights, she needs stamina to move and must stand still to refill it. Perhaps tie other stats to weight as well, such as increased HP.
This makes the player balance the risk of getting run down by enemies with the reward of more food (xp). As it stands, even if you get stunlocked by cakes and bashed from every other side by food, as long as you can sprint to the sack you're fine. There's no reason to not go back and forth to the sack clearing out every level 100%.
With these changes, a player needs to balance the long term need to get xp for the upcoming levels with the immediate need to get out of the one they're in now. Of course, the amount of "loot" in each level increases with each one, increasing both the risks and the rewards.