She is not.

ENDING ELEVEN: Big Things Come in Anonymous Packages

The next day, you receive a package at your door, with no return address or sender's name.
You take it up to your room in private and open it. Inside, you find a plastic vial of strangely glowing blue liquid and a single note besides it.

The note reads; "Drink me."
You shrug.
Bottoms up!

Immediately after the liquid settles in your stomach, you begin to feel a weird itch around your dick.
You take off your pants to scratch, and notice your genitals are glowing with blue light...and growing in size, too?!
Yes, in a matter of seconds, your puny dick and nuts steadily become bigger and bigger.
By the time it stops, you have a giant cock, thick all around and very hard, pointing forward, complete with huge hairless balls and muscular veins. Your cockhead has ballooned to the size of a grown mushroom. Your two hands do not cover the thick length.

Looks like you can finally lose your virginity to Heather after all!