From your description I would expect that the leak is on the high side, but there is certainly no guarantee of that.

There is ONE good way to find such a leak, but you will have to spend lots of money or find a shop that is equipped to do it.

With the system empty, put in about 2 oz. of R22 and then pressurize the system with nitrogen. Then you can find the leak with an electronic leak detector. R22 is MUCH more easily detected by such a sniffer than is 12 or 134 plus the entire system is then at high pressure making the leak even more detectable.

Good luck,