Your party looks really archetypical, which is not necessarily a bad thing. Archetypes are good for a reason.
Try being a halfling rogue. If you have a bad stat, put it in Constitution, but don't go below 10 (or 9, and drop your 4th-level ability mod into it). Just don't get hit. Try to keep your Int high, like 14 if possible, as in the long run, skill points will trump ability modifiers.
If you take my advice (and I've never played a full-time halfling rogue, so maybe a Con of 10 is suicidal), then grab Great Fortitude. If you find the dearth of hit points problematic, you can make room for Improved Toughness as your 6th-level feat.
I imagine Thanee's advice of 2-weapon fighting is good; if you're a halfling, you get a +1 size bonus on all attacks. I find that Point Blank Shot goes well with Improved Initiative, so you can be almost guaranteed a sneak attack at the beginning of melee. If you impress your party members by dropping someone at the start of a fight, they won't grumble about the fact that you mostly stay out of harm's way.
Clearly, I am a member of the hitting-and-running rogue school, and Thanee likes the beat-the-heck-out-of-em school. Both work. If you follow Thanee's advice, you probably want a higher Con score.