theres nothing wrong with mixing brands together unless it specifically says so, but i have xtend from scivation animal nitro for Universal whey from Optimum nutrition whey from syntrax and creatine...
Id up it to 3000, im around 130 pounds and only take in 2200 to maintain weight, up it to 3000 and see where it goes from there. You could always lower your intake. Its all about trial and error imo....
I use to be 90 pounds last year now im swole ass 130 pounder (not serious), bodybuilding is all about diet,training and rest. Try to stuff yourself every 2-3 hours(not with cokes, chips and empty...
dont you have lunch and break in between classes to eat? take protein shakes you can down in between classes or protein bars, and a protein meal like chicken and rice for lunch.
you have a good base, follow a routine and stay on it, try the 5x5 routine, remember to eat a lot and get lots of rest, get some multivitamins and fishoils in and whey is optional and your all set