HELP! Brakes still weak after bleeding (lots of times)

[curtains]

OK so I bought a 180sx a while ago that needed alot of work for cheap as chip, now the cars running and drivable and time to get the brakes to go.

I bleed them a few times (like 4 times) now and the fluid would have gone through the whole system a few times, and theres absolutely no bubbles coming out when I bleed them, I never let the master cylinder drop below minimum.

The brakes still seem to be soft and I can press them quiet far down (which is other cars you can usually just press them half down)

if i pump them a few few times then they have pressure (but i don't want to have to drive around and pump them 3 times every time i want to stop).

How do I know if my master cylinder or any other part of the brake system is broken or not, or what else may i have been doing wrong?

oh and another thing my master cylinder thing seems to make this minor noise when i pump it, kinda like a eeeeeee (but real quietly and slowly) donno if thats normal.