Two Weapon Fighting and BAB

Thanks for any help ahead of time. I'm finally running a high level character for Pathfinder, and am slightly confused about the number of attacks I get from a full attack. Just wanted someone to check my math and maybe tell me how a standard attack would look.

Assuming no magical/masterwork gear...

FULL ATTACK (two short swords) Rogue 8th Level
Weapon Focus (+1 for short swords)
Weapon Finesse (+4 for an 18 Dex score)
Two Weapon Fighting (-2 for the first attack and off hand light)

+6/+1, to +4/+4/+1 , to +9/+9/+6

So given WP, WF, TWF and rogue (8th level), a full attack with two short swords would be +9/+9/+6?

Not quite. The -2 applies to all of your attacks, including the one you get at "+1", turning it into "-1" instead. So the full attack with bonuses would be "+9/+9/+4".

You suffer the -2 TWF penalty to all attacks made during your turn. (Note that the penalty does not extend beyond the end of your turn, so it does not apply to attacks of opportunity).

So, rather than +9/+9/+6, it should be +9/+9/+4.

If you're an 8th level Rogue, you could (if you want) take Combat Trick as your Rogue Talent and use it to pick up Improved Two Weapon Fighting, which would give you an extra off-hand attack (and that would also be at +4 - so +9/+9/+4/+4).

EDIT: NINJAS! *shakes fist*

From the combat section

If you wield a second weapon in your off hand, you can get one extra attack per round with that weapon. You suffer a –6 penalty with your regular attack or attacks with your primary hand and a –10 penalty to the attack with your off hand when you fight this way. You can reduce these penalties in two ways. First, if your off-hand weapon is light, the penalties are reduced by 2 each. An unarmed strike is always considered light. Second, the Two-Weapon Fighting feat lessens the primary hand penalty by 2, and the off-hand penalty by 6.

When are you fighting this way? As a Full attack action.

If you get more than one attack per round because your base attack bonus is high enough (see Base Attack Bonus in Classes), because you fight with two weapons or a double weapon, or for some special reason, you must use a full-round action to get your additional attacks. You do not need to specify the targets of your attacks ahead of time. You can see how the earlier attacks turn out before assigning the later ones.

So you take the penalties the whole full attack.

Base is +6/+1
TWF (with the feat to reduce penalty) is +4/+4/-1
add WF and Finesse (+5) is +9/+9/+4

Thanks for the speedy input guys. For some reason, I had +6/+6/+1 in my head, but I've corrected the problem. My gratitude for the clarification.