Count the hours you did after your PPL was issued. Talk to your flightschool. You're entitled to log those hours as PIC. You are a licensed private pilot and the fact that they didn't let you fly more solo, is not a matter of legality, but rather airplane ownership. If you weren't ready to command an SEP-L, then you wouldn't have a PPL
The must rubbish advice I've ever seen on Pprune!
It has absolutely everything to do with who was the PIC and nothing as you describe.
If another pilot was onboard flying as PIC or you were receiving instructor your were not the PIC - they are single pilot aircraft which means only one pilot in command.
There are many pilot's who, unfortunately, just because they hold a PPL doesn't mean they are current and skilled enough to be PIC and a check out is normally required. If you don't pass that you won't normally allowed to be pilot in command of that aircraft and more dual will be required.
You can never log PIC on the basis "because I hold a PPL"
It's a simple question who was acting as Pilot in Command?