1997 Subaru Legacy soft brakes---

I start from the beginingchange the front pads and rotors like i've done for years--but this time I did one thing different and colapsed the caliper without breaking the bleed screw and pushed the fluid back up in the reseivor---i don't usually do it this way but my friend told me that is the way he has always done it----not sure if any of this could be the root of my problemso the symptons are that I have good pedal without the car running but as soon as I start it the pedal goes to the floorI bleed the system 2 times because of possible air in the line. Nothing helped--then I thought maybe it was the brske booster just from gathering info from around town----&300 later and another bleeding-Not the problem--i should probrably mention this is a right hand drive mail car--but not sure if that matters--any ideas would help---i have broke all lines loose around master cylinder and bleed system again but seem as if hard to get fluid to rear wheels