brake issue

[85sierraclassic]

so today and well yesterday i noticed my brakes felt funny, and then today they really felt like there wasnt much at all untill they were basicly to the floor. the brakes would work good but just nothing till almost full swing so i chech the fluid and its basicly bone dry. so i filled the master cylinder back up and that didnt do nothing, so i checked for leaks all over the place and everything was dry far as i could tell. then i decided to bleed the brakes and that went good on one side then thee other side desided to not let me get the bleeder opened, so i went and got a new caliper and blead that side.

well this is what i end up with. got the pedal feeling better but now it seems like it kinda pulls to one side but not bad, but the darn things gotta be losing fluid somewere and i cant seam to find it.

btw the trucks got hydro vac, instead of the vacume brake booster. so i dont think its possible to leak back in to it like a regular booster.?