The Potion. Demi shrinks you.

"Thanks so much for doing this for me" Demi says, leaning over to pick up another large box.
"No problem," I say, watching her walk up the stairs. I grab another box and follow her up the flight of stairs to her house.
She'd just moved in next door and asked if you could help her carry her things inside. You willingly did so, because secretly you found her sexy as hell. She wore tight Yoga pants and a top that only came down just beyond her large breasts, open via the deep neckline. Everytime she did anything it all jiggled slighlty, making you thankful for your self control. As the last of the many boxes were brought in Demi asked if you wanted to stay for a drink.

"Sure" I said taking any chance to spend more time with her.
She walked into the blank kitchen and pulled out two glasses and a bottle of wine, while I moved her couch and coffee table into a more reasonable place. I looked across to see her adding a few drops of something else to my drink. Lazily accepting it as something to add flavour or give it some more kick, I pass it off, more concerned with keeping the erection away. She walks over bending in front of me to place the drinks on the low table before sitting next to me. She leans over to pick up her drink, while I pick up mine, noticing her intently looking at me-
"WAIT!" she screamed grabbing the drink out of my hand, just before I took a sip.
"I need to do something else, would you mind if I tried on some outifits and you gave your opinion." Demi said very quickly, and very hastily.
"Sure," I said knowing this will be good.
She practically leaped from the lounge to her room which was the door closest to the right.

While she was gone I checked her cabinets for small bottle in which the extra drops were added from. I found it in the bottom drawer. The small glass bottles label read- Size Altering Solution. Grow to 9ft or 1 inch! Drink this with any liquid to change your size. Shrinking: serve when drinker is fully erect, any sooner will have no effect. Growing: serve when drinker is cold (approximately temperature - 3 degrees).
I read the label quickly.
Was Demi trying to shrink me? I wasnt fully erect when i went to drink before so that's why she slapped to out of my hand.
I heard footsteps and bounded to the lounge, right as Demi stalked out, wearing a booty shorts and a large D cup bra. She walked over in front of me, bent down, exposing her large round ass, before pushing the coffee table out of the way with her left arm, grabbing my drink with her left. She turned around, sat on my lap, legs spread, and leaned in. Her large breasts pushed my torso and head back as my hard dick got harder, she grabbed my face and poured the liquid down my throat. Suddenly my body felt on fire as Demi bit her lip, watching me intently. Almost instantly I began to feel weird, and Demi started to appear taller, bigger, thicker. I shrunk as she sat on my smaller lap, my head shrinking in between her ever growing breasts. She stood, pulling me with her. I know stood eye level with her massive chest, and honestly I didn't mind it.
Demi smiled wickedly at me as I stopped shrinking and gave me a huge (literally) hug.
"So. What do ya think, shortstuff?" Her body jiggling as she laughed. "What do ya think if your new size?" She said turning around.
"It has its perks" i said grabbing as much ass as I could. She swayed it slightly and almost knocked me over.
"Do you wanna get smaller? Small enough to be staring at my ass all day? Small enough to fit in my large breasts.? She turned around to face me and gave them a caress.
"How small can I be?" I asked. "How big can you get?
"As small as you want"