With the introduction of JAA, and now EASA rules, there is requirement to record to/ldg. This is not for a running total, but to monitor 90 day currency. You don't need to go back for totals, just start recording now, and anything you can remember recently.
To be fair, your instructors should know about this, and as a licence holder, you are also required to keep up to date of regulation changes.
If you are about to start commercial training, it might be worth buying a compliant logbook to use from now on.