I could care less
...is used incorrectly. Unfortunately this is often the case. I see this done all the time and it drives me crazy. As a child I misunderstood the intended meaning for years due to its frequent misuse. I would often hear "I could care less" and "I couldn't care less". I assumed that they were properly used and that their meanings were opposite. It took me years to discover that the only difference between them, as irony would hold, is that one was used "with care" and one was used "without care".
If you ignore what you understand "could care less" to mean, and evaluate it as if hearing it for the first time you will realize that it is making a statement exactly opposite of what you wish to convey.
In order to do something less, you must currently be doing that something to a magnitude which would allow you withdraw slightly without ceasing all together.
If I am juggling (one handed) three balls in the air, I "could juggle less" by subtracting one of the balls. I would then be juggling two balls. (juggling two balls two handed isn't REALLY juggling.) But at this point I "could NOT juggle less." If I were to remove one of the balls, I would then be tossing one ball in the air, which is certainly not juggling.
So, to convey your message, you must say "could not care less". This literally means one cares none or next to none.
Thank you for listening, and choose your words wisely. (People are judging you by them.)