Just noticed that you're doing a MAD version of the Slayer. You could choose to take the Ranger's Weapon and Shield style feats to ignore the prerequisites needed for TWF, ITWF, GTWF, and Shield Master (I think you can take it as early as level 6 with Ranger/Slayer) while allowing you to keep her as a STR focused character if you want to.
I thought about it, but Combat Tricks do almost the same thing (except for the huge Dex cost of course). It's still less efficient and you pay a heavy MAD cost, but the upside is that full Slayer progression gives me advanced talents which are pretty fun.
Sorry, didn't explain myself very well, I mean a Slayer can take a Ranger's combat style feats with their slayer talents rather than taking combat tricks.
This means you could do something like this (all Slayer):
STR 19 (+5) DEX 18 CON 16 INT 7 WIS 10 CHA 5
1 Shield Bash
2 TWF (Weapon and Shield Style- Slayer Talent)
3 Power Attack
4 Uncanny Dodge
5 Outflank
6 Shield Master
7 Improved TWF
8 Combat Reflexes
9 Imp Crit
10 Opportunist
11 Gt. TWF (temporarily wear a belt of dex +2 to qualify; you won't need to keep it on to still use the feat)
12 Bashing Finish
Etc.
Also means you don't need to take Shield Focus if you don't want it.