Just keep at it...
I've been playing for nearly a year now and i'm only waiting for the last girl from Silvanus.
Gotta be honest tho, I have the oppertunity to log in once per hour and drain my energy on the trolls. Then still it's only once per three weeks, that I get a girl.

I have 2 of the Epic Pachinko Girls (without the 10x) and all the event girls.
So just keep at it and I hope you'll be able to get all the girls.

It's just tough, especially if you can't log in often per day.

Girl Drop Rates are Waaaayy too Low-screenshot-jun-24-11-26-08.png