Govinda suspects that Siddhartha has found his own way to Nirvana without following a formal doctrine. Is this true, or has Siddhartha followed a predescribed path towards his goal?

This is true. Siddhartha has walked away from the Brahmins, the Samanas, even the Buddha himself. Siddhartha has learned that only he can discover the truth: it lies within himself seen only after desire and self have been purged away.