I buy pads for my wife, and often have to make sure that when I do, I buy the kind for menstruation and not for incontinence or leaking. They usually say right on the package, though I've now found that several say they are good for both. So read the labels!
Then, make an appointment with your doctor - if you have not already told her about this problem, you should.
I don't understand how like you said, "when you wet you wet big," cause in order to wet big your bladder had to of first been able to hold big. How do you hold big with weak bladder muscle?? Maybe first you should measure how much "big" really is by peeing into a jug to see what the actual amount is. If its small, maybe you do have weak muscle, if your able to fill say about 32 oz. then muscle must be strong and your just not taking the time to pee often enough.
Most leakage problems happen with females after child birth but you never stated your age, gender, or if you recently had a baby; nor did you state if this is a new problem or one that has always been with you.
I had a baby two months ago and I'm 32.
