Take your time to seek for the truth. Try to gather the very best (i.e., detailed, complex, annotated, etc.) Eastern Orthodox apologetic materials (electronic and/or printed) as well as the very best Catholic apologetic materials, compare them and see what comes out of it. Yes, there's a lot of work ahead of you but if you persevere, you will eventually gain certainty. And, of course, don't forget to pray without ceasing, asking for Divine guidance.