My view would be that assuming it’s a SP Aircraft you could only log Student PIC on the proviso that the instructor had signed each flight entry as such. But, I doubt that he would do that because although type rated you were not actually able to autonomously operate the flights IFR without his assistance and instruction, regardless of the fact that you were manipulating the controls. I think SPIC flights are meant to cover flights where the instructor effectively acts as an observer and does not actively participate in the flight conduct and management. In the same way that for logging PICUS on a MP type you are supposed to make the command decisions and show command CRM with the actual PIC acting as your P2 - but still the PIC!
Af the end of the day, if you don’t sign the tech log, you’re not the PIC I would say.
But don’t take my word for it - maybe talk to the school/instructor?