Interesting question! There are so many ways to go about trying to answer, and probably just as many answers. Each school or branch of Buddhism would take a different approach, and we can’t get into that here, so I will try and answer from a Jodo Shinshu perspective
Jodo Shinshu is a school of Mahayana Buddhism, and in Mahayana the ultimate goal is to become a bodhisattva, with the intention of attaining Buddhahood so that one can then compassionately help other beings freely, without the bondage of karma and ignorance. Traditionally, this is thought to take many, many lifetimes of difficult practice.
In Shinshu, instead of striving to attain enlightenment, the path consists of reflecting on and recognizing how far one falls from the pure path of bodhisattva practice. The term “bombu” or “foolish being” is used to describe the human condition. It would seem hopeless for such a person to attain enlightenment, and it is understood that a foolish being is unable to attain awakening by their own effort. However, the flip side is that we rely on the Amida Buddha, and by reciting the Name – Namo Amida Butsu – and reflecting on our own shortcomings, we awaken to the fact that we are embraced by Amida Buddha’s compassion. This is known as “shinjin” or “entrusting.” Although there are various interpretations, it is my understanding that this embrace transforms us, so that we are no longer blindly caught in ignorance, but instead are shown another way, towards compassion and the Buddha path. However, we are still foolish beings – in Shinshu, Buddhahood doesn’t occur until death when one is born in the Pure Land. But that’s a whole ‘nother article…
Maybe I haven’t answered the question. To look at it from another point of view, if you aren’t sure that you’re enlightened, then chances are that you aren’t. Traditionally, when Shakyamuni Buddha was awakened, he became omniscient, able to know all things, including his past lives and the karma of others. The Buddha is certainly portrayed as being aware that he had become enlightened. Some Buddhist traditions actually warn against mistaking spiritual experiences for enlightenment – it can be a trap that actually leads one into delusion rather than away from it.
Ultimately, I would say that in Shinshu it is important to understand what enlightenment entails, as well as the path towards it, whether it is the Six Paramitas, the Noble Eightfold Path, the Nembutsu, etc. In our own lives, we want to deepen our understanding of the Buddha and the Dharma, to try and put the Buddha’s teachings into practice, but we also need to be reflect on ourselves, on our thoughts, words, and deeds, being honest and seeing ourselves as we are.