Andrea let out a choked growl as your seed went down her guzzle, her arms trying to thrash free from your grasp. You yourself aren't really sure you're comfortable with what you've just done, forcing yourself like this onto your crush even though these are definitely not normal circumstances since she lost her human mind to feral instincts. If this does turn out to work, you're definitely going to look for another way to get this antidote to work -- ethics aside, this is a pretty dangerous way of administering the antidote anyway.
In the meantime, you let a low growl through your lizard maw as you use your increased strength to pin Andrea down, watching vigilantly as she continued to struggle against her restraints, her growls of lust gradually changing into growls of what seemed like pain as her lizardwoman body seemed to pulse under your arms. You hold your own instincts firm -- you didn't give up all those sleepless nights and your female human body just to screw up and throw it all away now -- as you see her body get a bit more slender, her breasts grow a bit more still but her nipples cease leaking that darned lizard milk, her thrashes becoming more like muscle spasms as her movements stop trying to break free so much as, you eventually realize, trying to get away from you. Andrea manages to get loose and scrambles backwards to the wall, her lizardwoman eyes showing none of the feralness that had overtaken them before.
She eventually stops making sudden violent moves as she seems to need time to regain her bearings. Your optimism is guarded as you slowly approach, though you don't even get six inches closer before Andrea lets out a sharp warning call, one immediately followed by her eyes widening in alarm as she looks down and stops dead in her tracks staring at her claws. She lets out a growl that almost sound like a questioning "What?" as her claws slowly reach up and touch her lizard maw. Her eyes shift to you -- you hold still so as not to alarm her any further -- and then to a nearby metal lab table that had been knocked over at some point; you can easily see her shock at the lizardwoman visage looking back at her in the reflection, her eyes looking down at her changed body.
On one hand, the antidote finally seems to have worked -- Andrea's humanity seems to have come back, at least in her mind. But she's definitely confused and maybe scared about what happened to her -- this lizard apocalypse has gone on how long now? and to realize you're now one of them, even if you're not acting like one yet, must be terrifying. And who knows who else is still in this facility and could have heard this commotion -- a lizardperson or the military would be make this tense situation even worse, probably.