Loosing brake pedal randomly..

so one day my seen that my caliper seal was broken and i had to get a new one. so i just keep filling my brake resivour up when the light went on until my caliper i ordered came in.
My brake light did not turn on one day and i ran it empty and lost all pedal. So when i filled it up that time. i still had no pedal even AFTER bleeding through a half gallon of brake fluid lol. (gravity bleed, machine vacuum and mechanically bleed all 4 and BMC). So along getting a caliper i got a reman master cylinder.

I replaced it the next day and i STILL had no pedal. I bleed it all 3 ways again still NO pedal. so i just drove it around in a parking lot for a few hours and BAM randomly i got a pedal again.

It has been 2 months and now i am slowly loosing a pedal and my e-brake does not work. NO LEAKS anywhere and everything is tight. i have half a pedal but it is going away. The only thing i noticed is my reman caliper…it is all sort of rusty now. while all my other OE calipers are not. i live in Florida inland no rust.

What in the world could it be better not say booster lol wouldn't the pedal be hard if it had no boost?