Sounds like about the right amount of oil. Too much oil will not directly jam the compressor. Its downside is to reduce heat transfer in the evaporator and condenser, which can cause high-side pressure to rise, which then fights the compressor. You need to read the operating pressures. I bought the Harbor Freight gage set for ~$20 on sale a few years ago, and use it all the time on all my cars, but you can get just a high-side gage cheap.

What type oil did you use? A downside of PAG is that I understand it forms corrosive acids if it ever gets moisture. That can happen if you lose refrigerant and don't take care of it right away. You also must buy the correct viscosity. I read that PAO 68 is the best oil to use today. Works with any refrigerants, stays put in the compressor better, doesn't absorb moisture, and works for any required viscosity. Can buy on ebay. I bought Duracool's version.

I hope you didn't start with a dry compressor and then just add a can of "oil recharge". Best to pour the oil directly in the Sanden fill port, per their manual (can down-load on-line). Try spinning the compressor by hand (engine off, key in your pocket). Spin the inner part (not pulley w/ V-belt). It should spin fairly easily and you shouldn't feel a rough bearing or dragging pistons. If really determined, remove the refrigerant hoses and verify that you feel pressure build up on your thumb over the outlet and suction on the inlet, but that means dumping your refrigerant (illegal w/ R-134A, OK w/ my Duracool).