I agree, get a leak test performed on it. Shops can easily do this with a special dye and UV light.
The compressor is a solid piece of machinery, and the only way they get trashed is by running it completely out of oil (oil is mixed in with the Freon to keep the compressor and seals lubricated). If they wear out, they'll make noise or rattle and vibrate. If the compressor isn't making noise, then it is fine and your problem lies elsewhere.