Adventures in film

I've been shooting with Fuji Neopan 400 for the last two weeks, and I've been getting some very strange results. The first week I shot one roll at 400 ASA and processed it in D-76, 1+1 for 9.5 minutes, the number listed in the massive dev chart. The negative turned out with less contrast than I was expecting. When I went to print the film I had to expose the paper for 60 seconds! Even then the photo still wasn't very contrasty. The following week I shot two more rolls at 400, but this time I developed them for 11 minutes. This time the negative turned out more contrasty than I was expecting. Also, the paper only required 6 seconds. Holy hell! There are a number of reasons that I can think of why this happened:

1. the developer I used for week 1 came from a half empty bottle, while the developer from the second week was from a full bottle, therefore less oxidation.
2. I agitated a lot more on the first week than the second.
3. I was using pearl RC paper for the first week and matt FB paper for the second week.

I think I have to work on being consistent.