A/C (Freon added), Please help.

[urcbmw8]

I have 2001 X5 4.4i and recently my AC is not cold enough so I added freon today and freon is R134a (12oz). First I added 12oz can of freon and then I felt that it was still not full, then I add a second can of 12oz freon while I was charging freon. I heard sound pop and then all gas like white smoke coming from underneath the car. I believe I over-refilled freon, then I bleed out some freon. I would like to know that if I over-charged the freon, will it damage ac line or compressor? If not, what kind of damage on my ac system? Did my ac line blow out? But, I still have cold air inside the car when I turned on AC. Last, what is the required psi or air pressure for low and high? Please advise and thank you very much for all inputs.