My girlfriend promised she was done taking the experimental hormone supplements after her boobs broke a G cup bra in the middle of dinner from growing. But every morning I wake up to her another few inches taller, bustier, stronger, and when I bring it up she gets aggressive m last time it ended with me pinned to the bed
Your girlfriend really shouldn't have promised to stop, because there's no way that was ever going to happen. I mean, come on. In the middle of dinner, in a public place, she felt her body grow and expand until her G-cup bra, a bra that's already more than double what people would consider average, broke from the strain. She didn't just overflow it. She didn't just stretch it out. The bra fucking broke. Her growing curves were too much for it to handle and it gave up entirely. I can only imagine how her eyes must have fluttered, how she grabbed the edge of the table, how she clenched her thighs together to try and squeeze out as much pleasure as she could from the feeling of growth. When her eyes finally opened and she glanced around the room, all of the looks, lustful and jealous in equal measure, would have just stoked the flames inside her to even greater heights. To go through all that and then, afterwards, promise to never experience that kind of pleasure again? Did you really think that promise was going to hold?
What happened that night was a revelation to her, a feast for the senses with such richness and decadence that it permanently unlocked a part of her mind. For her to have to go back to her normal life would be unbearable. Being big is fine—good, even. But growing bigger? Feeling herself expand in every direction? Knowing that she's making a spectacle of herself and that no one can keep their eyes off of her growing body as it becomes a beacon of power and femininity? That's true pleasure, distilled into its purest form. She can't just give that up.
Your confrontations are only making it worse, too. Honestly, I don't think she really cares what you think about her growth. A goddess doesn't concern herself with the opinions of a flea. When you bring it up, however, it does give her a great excuse to push back on you. You said she pinned you to the bed, underneath her towering, curvaceous body? She doesn't want you to stop protesting her use of the hormones; all she wants to do is prove—to you, yes, but mostly to herself—that she's getting even stronger. Every time she pins you to the bed or backs you up against the wall, it gets easier. She's getting taller, bustier, stronger, but from her perspective, you're getting smaller, lighter, weaker. It won't be long before she'll be scooping you up and lifting you into the air, moaning at just how easy it is, reminding her how much stronger she's gotten.
You're not going to be able to get her to stop. That ship has sailed and disappeared over the horizon long ago. Doing nothing will give her license to keep going and fighting against her growth will simply remind her why she loves growing in the first place. Taking control will be more like a game to her than anything else, a game that gets easier with every added inch.