Actually, most were confirmed by Taylor....
Some seem like they were PR. #8 and #9 may just have been PR but were confirmed by Taylor's PR people and Taylor.
#12 is the only one without photos.
1. Joe Jonas - confirmed by both of them
2. Taylor Lautner - confirmed by both of them
3. Lucus Till - MTV interview with Lucus he said they dated.
4. John Mayer - confirmed by both of them. Was "Dear John" about him?
5. Cory Monteith - Dated for months, many photos, they say they were just good friends. I count this as dating.
6. Toby Hemingway - There are intimate photos but no confirmation from either that they "dated".
7. Jake Gyllenhaal - Dated for a year, many photos and video. [He should get a co-write credit for part of RED.]
PR RUMOR? 8. Zac Efron - this one may have just been PR. But if it was really just movie promo, they looked like they were are couple and said they were dating.
PR RUMOR? 9. Garrett Hedlund - photographed together at dinner.10. Eddie Redmayne - confirmed by both of them.
11. Conor Kennedy - photographed together.
RUMOR 12. Patrick Schwarzenegger
13. Harry Styles - they are off skiing together. Lot of photos and video.
And there are at least four more boyfriends....
She has mentioned other boyfriends in interviews: Kyle McKinley and Riley Howell.
She said "Tim McGraw" was inspired by ex-boyfriend, Brandon Borello.
"Picture to Burn" was written about an ex-boyfriend who never let her drive his pick-up truck, a redneck. [Not clear who this is.]
"Should've Said No" was about an ex-boyfriend that cheated on her, Sam Armstrong, and, in the CD booklet, every S, A, and M was capitalized if it was in the correct order.
ETA: I really am amazed at how nice the gossip press is to Taylor. The only exception was the Conor Kennedy "dating" or whatever that was. He was in high school! Seriously odd. But can you picture what would have happened if Miley Cyrus was chasing an 18-year old high school kid who was a Kennedy and bought a house near theirs?