Is doubting, even for a moment, the attributes of Allah mentioned in Surat Al-Ikhlas considered disbelief, given that I immediately rectified it by saying, "There is no god but Allah, alone, without partner; to Him belongs all sovereignty and praise, and He is over all things competent"?

What you mentioned does not lead to disbelief. We advise you to stay away from obsessive thoughts and not to give in to the devil in this regard. Learning is the most important thing to seek, and it requires effort, time management, and a good choice of teacher and book. It is essential to engage with the Quran and Sunnah and what has been derived from them. The Messenger of Allah (peace and blessings be upon him) said: "Knowledge is acquired through learning, and forbearance through practicing forbearance. Whoever seeks good will be given it, and whoever guards against evil will be protected from it." This means that true knowledge is that which is taken from the prophets and their inheritors through learning.