I looked over the sheet and it looks good. Thank you for breaking things down so cleanly for me. The only comments I have are on the notes.
No problem with the Book of Ancient Secrets.
I am going to nix the dragon familiar as written. That's a powerful little guy compared to the normal options for familiars outlined in the spell. However, I will let you reskin the stats of any of the flying familiars specifically mentioned in the spell as a dragon. So take raven stats (for example), but narratively, it's a small fey dragon. I'll allow the dragon to have narrative freedom to do magical acts (breathe fire or similar), but not in combat situations.
For example, I would be fine with you holding out a pipe to your familiar who breathes a bit of fire to light it before you bring it up to smoke it. I wouldn't be fine with it casting Color Spray on its own power in combat.
If you use the familiar in combat, it will only have the stats of the flying familiar (as per the spell) that you choose to use for it. However, you can describe its actions however you like. For example, if you wanted to use the familiar to make the Help action to give Advantage to the next attack against a creature, you can narrate that as the dragon breathing a sparkling cloud in the opponents face before someone strikes. It's just in the mechanics of the game, that action was not a breath weapon; it was the help action.
Does that make sense and does that work for you? If not, feel free to choose a different ritual for that slot.
