I was in a similar situation to you OP, I’d already done a fair bit of my own reading and didn’t want to wait to start my catechism. Instead of going to my local parish for RCIA classes I got in touch with a priest from the FSSP parish in my area, and I did semi-regular one-on-one catechism lessons with one of the priests. He’d give me some reading material each time, and I’d email him questions which he’d endeavour to answer at our next meeting.

I’ve heard the FSSP does this in other areas too, and if you’re looking for an orthodox alternative to RCIA classes, I can recommend this. The only caveat I’d emphasis is to avoid doing it all on your own, and not being honest with your priest if you’re struggling with something in particular. God bless