Excellent! That said, all I have to deal with is, find where the leak is and top off the system. I just hope that it doesn't leak in the internals of the compressor.

Is it possible that the refrigerant just disappears? Because I already visually inspected the entire system but did not see any visible and obvious signs of leaks. But I haven't used any UV light yet.

vstech is correct, and your gauge readings confirm it.

Unfortunately, the most common leak site is the shaft seal on the compressor. The R4's do that. Fairly easy to do (Autozone tool loan program), but requires recovering the refrigerant. Use the new double lip seal if it is the shaft seal.