Farrah Abraham -- Yes, I Made a Porno ... But I Want Millions to Release It

Farrah Abraham is finally copping to shooting a full-on porn -- with A-list porn star James Deen -- but says even though it was intended for her personal scrapbook ... she's willing to sell it for $2 million.

The ex-"Teen Mom" star's reason for shooting the XXX video is simply the best ... telling TMZ she wanted to immortalize her smokin' hot 21-year-old body -- for her personal collection -- so she could look back on it when she's old.

Guess Olan Mills was booked?

Farrah, who initially denied a sex tape existed, says she's pissed at her penis-for-hire -- because Deen let the cat out of the bag ... telling our camera guy the whole staged shoot was Farrah's idea.

Farrah says she wants nothing to do with Deen now (we suspect that's mutual) and took a parting shot, telling us -- "If my ex-boyfriend Derek were alive, I would've rather it had been him with me."

Farrah's baby daddy Derek Underwood died in a car accident in 2008.

As for the sex vid going public ... Farrah says her lawyer is dealing with a porn company, and she "will not be settling for anything less than a couple million" bucks.