It's weird, on my main I didn't do any fates until 50. Like zero. I had to farm my pants off to get rank / GC weapon once I hit 50 (I mean I know I didn't "have" to but I wanted it). I still finished with about 20ish quests around the 40+ area for my next guy to hit. I hit a brief point around 47-48 where I couldn't continue the main quest because it was level locked, but came back.

Didn't do any leves other than the quest to unlock each tier in each zone.

I think you're missing some.