I'm happy I found you here, as I rarely had a constructive exchange of ideas on the internet....
No problem, I wish I could be playing right now, so it's nice to be able to still at least work on builds.
EDIT: I was thinking about this build up to level 15th
I put what I gain with class levels in brackets
1. Rogue (SA 1D6, Trapfinding) Feat: TWF
2. Swashbuckler (Weapon Finesse)
3. Swashbuckler (Grace / Arcane Stunt) Feat: Dodge
4. Swashbuckler (Insightful Strike)
5. Rogue (Evasion, Feat: Weapon Training (short sword)) Feat: Quick Draw Skill Trick: Hidden Blade
6. Rogue (SA 2D6, Trap sense +1)
7. Rogue (Uncanny Dodge, Feat: Fast Stealth) Feat: Titan fighting
8. Rogue (SA 3D6)
9. Rogue (Trap sense +2, Feat: Combat Trick (Improved Initiative)) Feat: Darkstalker Skill trick: Acrobatic Backstab
10. Rogue (SA 4D6) Skill trick: Back on your feet
11. Rogue (Improved Uncanny Dodge, Feat: Combat Trick (Improved TWF)) Feat: Craven
12. Rogue (SA 5D6, Trap sense +3)
13. Rogue (Talento: Opportunist) Feat: Savvy Rogue
14. Rogue (SA 6D6)
15. Rogue (Trap sense +4) Feat: Staggering Strike
Then I'd go on with the TWF tree.
Is there something wrong with this order?
PS: Combat Trick is a rogue bonus feat that lets me get a fighter feat. Weapon Training is a rogue bonus feat that is equivalent to Weapon Focus.
This way I'll fight with two short swords with only -1 on hit checks.
I think you should be grabbing Improved Two Weapon Fighting earlier than post level 15. Maybe not immediately, since the bonus to hit will be so smal at first, but certainly by level 12 I'd think. GTWF isn't terribly important, barring going past level 25, you're unlikely to hit with it much.
Weapon Focus is ok...I just think there are better things out there. I'd save that for a level where there's nothing you want more (or you do want something more, but can't obtain it yet).
Staggering Strike is a key component to the build and sheer survival, I would take it at the earliest level possible.
Improved Initiative, like Weapon Focus isn't a bad feat per say...but there's more important stuff you would want to take first. Improved Initiative is more important for archer rogues, who rely solely on loss of dex / flatfooted conditions to get sneak attack. You have flanking and feinting to help out, and Imp. Init only really helps you get SA on the first round (and surprise round, if applicable), when you're unlikely ot be able to do the full attack SA you're built for anyway.
I'm still not sure it's worth 2 feats to get +4 AC against a single opponent. But if you do want to stick with htat plan, you should be taking Titan Fighting in as quick succession to Dodge feat as possible. Dodge itself is terrible, the only reason to take it before more important feats would be for Titan Fighting. You should be getting Titan Fighting at level 5 with the listed build (side note: Why do you think Quick Draw is even important for you? Planning on doing some dagger throwing, too? Not sure it's worth it just for Hidden Blade). Alternatively...that Combat Trick class feature to get a Fighter feat? If you instead used that at level 9 to pick up Dodge, you could in the same level up also use your general feat on Titan Fighting. Just for example.
Also...take Craven as early as possible. Seriously.
What is Darkstalker? Don't know that feat.
EDIT: Ah, missed that you got ITWF at level 11 via class. All is well with the TWF tree, then.