I'll just use one scripture you posted a portion of....
2 Cor 12
Sufficient Grace
12 Boasting is necessary. It is not profitable, but I will move on to visions and revelations of the Lord. 2 I know a man in Christ who was caught up into the third heaven 14 years ago. Whether he was in the body or out of the body, I don’t know, God knows. 3 I know that this man—whether in the body or out of the body I don’t know, God knows— 4 was caught up into paradise. He heard inexpressible words, which a man is not allowed to speak. 5 I will boast about this person, but not about myself, except of my weaknesses. 6 For if I want to boast, I will not be a fool, because I will be telling the truth. But I will spare you, so that no one can credit me with something beyond what he sees in me or hears from me, 7 especially because of the extraordinary revelations. Therefore, so that I would not exalt myself, a thorn in the flesh was given to me, a messenger[a] of Satan to torment me so I would not exalt myself. 8 Concerning this, I pleaded with the Lord three times to take it away from me. 9 But He said to me, “My grace is sufficient for you, for power is perfected in weakness.” Therefore, I will most gladly boast all the more about my weaknesses, so that Christ’s power may reside in me. 10 So I take pleasure in weaknesses, insults, catastrophes, persecutions, and in pressures, because of Christ. For when I am weak, then I am strong.
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This directly refutes that Grace isn't sufficient, and is again Paul not boasting.
Many Scholars believe Paul is referring to himself in third person, that he might not explain that He was the man caught up within 3rd Heaven, as this would be boasting of self....
But I assure you, Paul only boasts of Jesus and exalts people bathed in His mercy to exalt Jesus.
In other words...
Paul only exalts and boasts of God.