I can't see the clutch activating, its too close to the side of the engine bay, but I can hear its pitch get slightly lower when I kick on the a/c. Possibly something wrong with the condenser?

 

Those recharge cans are about the biggest waste of money you can do.
There is only one possible reason why you need a recharge. Your system is leaking.
You can't see the leaks.
Take it to the shop (a good shop, or the dealer) and get an estimate. You may find it's not worth it.
They have refrigerators in the junk yard, 50 years old, which still work. As long as your seals are good, you will have no leak. When your seals or hoses go bad, you leak, and can't see it.
Putting in more R12 or R134 is a waste til those leaks are fixed, and it can be expensive.
A/c and auto trans are about the only thing the diy'er can not do.
dc