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RW, I've reread your posts a few times, and have a couple of thoughts:
If the bar is too far forward or too far back in the palm you're going to get uneven stresses, and that can happen particularly with small hands (I don't think you have small wrists, mine measure around 6.25" or so and I've got big paws for a chick, 8" from the very bottom of my hand to the very tip of my middle finger).
It sounds like you're problem may lie in a) where the bar is falling into your hand, and b) your tendon of the palmaris longis. I read an article about bench pressing that said you should feel like you're trying to squeeze your hands right through the bar, that's tough for a person with smaller hands (I've included the website for that article a little lower down).
I just went downstairs and tried playing around with different grips on my barbell, if I "scooched" too far to the foot of the bench and had my arms at somewhat less than 90 degrees when in full lockout I ended up with my hand in a hyperextended position that caused discomfort in MY wrist, and I never have hand or wrist pain when I bench, and I type for a living.
I think you need to tweak your form, check out this article, really good, very detailed:
http://www.fitnessscape.com/Big_Benching.htm
(not a link, you'll have to do a c/p)
A couple of points:
1. Make sure the bar is in direct line with your eyes.
2. Feet have to be flat on the floor, your body should be a "table" from shoulders to knees. If you can't do that -- the bench is too high, another common problem -- then get solid blocks or plates under your feet.
A real ego buster is realizing that benching IS NOT about the weight, it's about form (and this is true, even if you're a powerlifter). If you're using a weight that's too heavy for you to hold without hyperextending your wrist then your form may need some work. I had to admit something very similar to myself recently and was amazed how hard it was for me to admit this. I didn't want to go down in weights!!! But my problem was that my pecs weren't being fully recruited in benching, and isn't that the whole PURPOSE to benching??? It's a CHEST exercise, not an ARM exercise! If you're not using good form, the majority of the weight can be handled by every muscle BUT your pecs.
It took getting a real grip on WHY I'm lifting weights to get myself to drop plates in favor of going to a wider grip and really focusing on pectoral squeeze, what a HUGE difference.
Any pain that you're only getting while you're doing something (but goes away when you stop doing that activity) means, essentially, don't do that or you're doing that wrong. Ask your spotter critique your form (if you're benching 125 you better have a spotter!) If they don't see a problem, have someone video tape you from a couple of angles, I'll bet you see something that needs change.
If the bar is too far forward or too far back in the palm you're going to get uneven stresses, and that can happen particularly with small hands (I don't think you have small wrists, mine measure around 6.25" or so and I've got big paws for a chick, 8" from the very bottom of my hand to the very tip of my middle finger).
It sounds like you're problem may lie in a) where the bar is falling into your hand, and b) your tendon of the palmaris longis. I read an article about bench pressing that said you should feel like you're trying to squeeze your hands right through the bar, that's tough for a person with smaller hands (I've included the website for that article a little lower down).
I just went downstairs and tried playing around with different grips on my barbell, if I "scooched" too far to the foot of the bench and had my arms at somewhat less than 90 degrees when in full lockout I ended up with my hand in a hyperextended position that caused discomfort in MY wrist, and I never have hand or wrist pain when I bench, and I type for a living.
I think you need to tweak your form, check out this article, really good, very detailed:
http://www.fitnessscape.com/Big_Benching.htm
(not a link, you'll have to do a c/p)
A couple of points:
1. Make sure the bar is in direct line with your eyes.
2. Feet have to be flat on the floor, your body should be a "table" from shoulders to knees. If you can't do that -- the bench is too high, another common problem -- then get solid blocks or plates under your feet.
A real ego buster is realizing that benching IS NOT about the weight, it's about form (and this is true, even if you're a powerlifter). If you're using a weight that's too heavy for you to hold without hyperextending your wrist then your form may need some work. I had to admit something very similar to myself recently and was amazed how hard it was for me to admit this. I didn't want to go down in weights!!! But my problem was that my pecs weren't being fully recruited in benching, and isn't that the whole PURPOSE to benching??? It's a CHEST exercise, not an ARM exercise! If you're not using good form, the majority of the weight can be handled by every muscle BUT your pecs.
It took getting a real grip on WHY I'm lifting weights to get myself to drop plates in favor of going to a wider grip and really focusing on pectoral squeeze, what a HUGE difference.
Any pain that you're only getting while you're doing something (but goes away when you stop doing that activity) means, essentially, don't do that or you're doing that wrong. Ask your spotter critique your form (if you're benching 125 you better have a spotter!) If they don't see a problem, have someone video tape you from a couple of angles, I'll bet you see something that needs change.
Flexed back. Yes ma'am I know. But the weight is too heavy for my wimpy assed forearm flexors. If I try to keep my hands inline with my forearms the bar feels like its slipping. I'm flummoxed!
I'm so happy you found the solution. 
