There is a difference between authority and inerrancy. Scripture is inerrant. The church isn't. Therefore whatever Scripture says has the authority of God behind it. The same cannot be said for whatever the church says. That includes the church's determining what is and isn't Scripture.
I never trusted an authority in itself to tell me what is and isn't canon. I read the books myself. I took the testimony of the Protestant churches to heart as part of that process. I tried reading non-canonical works. But Scripture speaks unlike any other book. It makes better sense of the world than any other book. It reveals a path of salvation unlike any other, and all the individual books speak of the same truth, different voices, without contradiction. The manuscript evidence shows that there is no significant alteration or variation in the texts over spans of hundreds or even thousands of years. It doesn't trouble me that some churches have different canons. Just like I'm not bothered by some people who say that 2+2 might equal 5. (They do exist.) I weigh the evidence and make a rational judgment. Many other saints down through the ages have made the same judgment. Christ preserves His church. I have not seen any evidence to suggest the Protestant canon is a novel tradition.
"Unless I am convinced by Scripture and plain reason - I do not accept the authority of the popes and councils, for they have contradicted each other - my conscience is captive to the Word of God. I cannot and I will not recant anything for to go against conscience is neither right nor safe. God help me. Amen." -Luther
