Advice for researching Ancient Christianity.

Hello brothers, I am finishing the process of catechism, but before I fully committed I wanted to be absolutely certain that I will stick with Orthodoxy for my whole life, I do not want any chance that I will switch denominations later.

Protestantism is easily ruled out as being the true church, so the only true competitor with us to the claim is Catholicism. I have already researched our theology and history quite extensively, but they also make claims to historically being the true church. I would like to do one final large analysis of the early Church and Christian teaching to dispel any little doubt which still remains in my mind.

The main points of focus for me will be the Papacy, the Filioque, and the Ecumenical councils. I have found that unbiased research as well as just extensive information on these things is hard to come by, so I’m curious if anyone can recommend good websites for researching the full history and the main points I mentioned with as little bias as possible. The best resource I’ve been able to find so far is “https://christianhistoryinstitute.org/study”, which is a Protestant organization but doesn’t seem to have much bias.

Any help with this would be greatly appreciated, Thank you, and God bless.