With Jessica's consent, you begin carefully dosing him with tiny sips of each potion, under the theory that a small dose will only cause a partial change. You're right on that count; one potion gives him a frog's webbed hand, one causes a half-formed fly's wing to sprout from one shoulderblade, one puts gills on his neck.
What none of them do is make him any more human, or show any signs of re-switching his gender. By the end of the experiment, poor Jessica is a horrifying chimera of a dozen different disgusting creatures; even Aaron, desperate as she is, admits she'd rather put up with her wings than try those potions.
"Well," Jessica groans, staring down at his twisted mess of a body, "it was a good idea to save that cat potion, because boy do I need it." He picks up the potion in his one functional (albeit flippered) hand, uncorks it with his lamprey teeth, and downs the contents.
Mere moments later, his skin is sprouting a coat of charcoal-grey fur as his body returns to a normal humanoid shape, all the effects of the potions vanishing into his ever more feline body. In under a minute, he is a cat-person like you, except male, grey, and unclothed.
His grey fur is accented by short, thatchy dark brown hair on his head, and a downy white patch running down his front, from the underside of his chin to the base of his tail. Like you, he's more slender and athletic in his build than beefy and hyper-masculine. You try not to notice that he's naked, but it's hard.
"So," Aaron pipes up, "what do we do now?"
You think for a minute. "Well," you reply, "obviously the potions are a bust, at least for getting us back to normal. But here's something I thought of: when I was working as the witch's maid, I dropped one of her potions, breaking it. It vaporized, and when the smoke cleared, I was an anime-style cat-girl."
"You mean the potions work by contact as well?" Jessica asks. You nod. "So," you reason, "if we can chuck one of these at the witch, it might change her into something harmless. If one of us can get inside and hide until she's asleep, she should be an easy mark."
"I'd offer," Aaron says, "but I'm obviously not suited for throwing anything." She swishes a wingtip for emphasis. "Sorry."
"It's all right," you say. "It's not your fault you don't have hands. Anyway," you continue, looking at Mike and Jessica, "it's up to one of us. We've got until just before nightfall to decide, so be thinking about it."