How are you guys seeing block history that far back, and how do you see you havent been credited? Do you have a program downloading the stats and adding them up to compare against the website?
I don't know how far you can go back, but if you use the ?history=NNNN argument on the stats you can go back a way more than the standard display - example:
https://mining.bitcoin.cz/stats/?history=1000It's pretty reliable.