As long as your rated in the aircraft and are flying which I would assume 99% of the time you are you can log PIC. The instructor would be logging dual given, and PIC.
Also as a suggestion you might consider asking your CFI to show you were in the regs he is getting his information. Use it as a learning experience, and If you really want you both could call the FSDO during a ground lesson and ask them. Any flight instructor worth their weight should have no problem showing you where they found it.