I gave my grandma's sister a lactating pill

I staid one summer at my grandma's sister Mary, in the countryside. It was a nice way to escape the city and enjoy simple things.
Mary was in her 60's, not thin, not chubby, her tits where saggy but meaty and her nipples where poking through her clothing. She didn't mind about her clothes so cleavages and tit slips happened often, witch for a teenager full of hormones where hard times. Literally.
I was always attracted by tits. When i was small, my grandma used to undress and encouraged me to touch her boobs. I've heard that she even gave me her tit to suck when i was a baby so i would stop crying.
My whole adventure started when i accompanied Mary to the doctor. In the office there was a woman who adopted a baby, wanted to breastfeed him and was looking for a way to induce lactation. She bought some medicine that will do the job and she took it to the doctor to see it. She opened the bag and she managed to spill all the pills on the floor. I jumped to help gatering the pills and gave them to her, except one, witch i hid.
- Probably it's gone in the drain, said the doctor.
We got home, Mary cooked something and we eat. I got up to take some juice and Mary said she wanted some. An ideea caught roots in my mind since i was in the doc's clinic. I mixed the lactating pill in Mary's juice and gave it to her. She drank it all, in one sip.
I didn't take much notice. I thought the pill was ineffective or it needed more of them so it came out of my mind.
But after a few days i noticed that Mary began rubbing her nipples more often and her tits looked bigger.
One day, at noon, we where in the garden arranging the haystacks. I noticed some disconfort at Mary. She looked constantly at her chest.
She called me to rest on some hay. As we stayed there, she said:
- I know where the missing pill went, looking at her chest. And now, you caused me a problem. Come on, lay your head on my lap. You are part of the problem, you will also be part of the solution.
I laid with my head in her lap. She unbuttoned her robe, exposing her thick breast with veiny light pink areolas. I took her nipple between my lips and tried to suck but no milk came.
- Not like this. This is not a straw. You must take more of the tit in your mouth and suck with your tongue.
I latched on her tit like she told me and to my surprise, my mouth got full of milk. As i suckled her tit, my wood began to get harder and Mary started to breathe much faster. I rolled her on her back and climbed on her, without letting the milk bag off my mouth. I slided my hand between her legs and noticed she didn't had panties. I lifted her robe, took my pants down and pushed my dick in her.
I started fucking her, with ample moves. She was panting, grabbed the other tit in her hand and milk sprayed upwards making a mess of me and her . She pushed my head in her chest. I didn't even nedd to suckle, milk came into my mouth from the pressure of her grip.
We finshed almost the same time. Mary rolled on her side, grabbed my head and pushed her tit in my mouth.
I sucked both her tits dry, playing with her nipples like a baby. When we finished, we dressed and we resumed our chores.
Later in the evening, we layed in bed and Mary gave me tit again.
- Do you have any of those pills left? I would gladly make your grandma Nina take one and milk her fat udders like a cow. She and her bright ideas of flaunting her milkbags to you.
- No, Mary. That was the only one i got. But maybe the fresh mother didn't used all of them.
- Yeah, maybe..will see…