No it's not broken or anything, high rarity girls is normaly difficult to come out.
It's will be more difficult in future so be prepare.

There are 2 way you can get SSR in this game by my POV.
1. You are lucky bastard that can get SSR from every single roll.
2. You have big wallet to buy unlimited premium roll.

Anyway I already complete quit this game, since it has less automatic control.