As has already been said, we'll be able to help you a lot more if you upload your work for us to see!
The sad fact is that there are too many people working in design for you to always come up with something original, and when the brief is to simply combine two very common initials, you might be out of luck. I think it's important to have something unique, but it might have to be that you make it unique in the way you present it rather than how you combine the letters.
Alex had this problem with his brand (how is that going?) but he managed to come up with something that well presented, even though the letter combination wasn't 100% unique, which is fine, because a lot of the time it's impossible to be unique!