"And if white going into the open Sicilian is really as common as you say, then why would the OP be having trouble in the anti-Sicilians"
Because they aren't challenging for black.
Whether they're challenging depends on the person who's playing them. There are many professionals who specialize in one of the anti-Sicilians. There's a very pretty FM on youtube named Alisa Melekhina who specializes in the Alapin and has videos on it. Roman Dzindzichashvili specilizes in the Grand Prix attack. IM Lawrence Trent is an expert in the Smith Morra, etc etc.
If you approach your particular anti-Sicilian thinking it's going to automatically give you an advantage just because it's called an "anti-Sicilian" then no, it won't be challenging for black. If you actually put the time and effort into learning it and practicing with one, only then will it live up to its namesake.
That might be true, but I just want to have some idea of what others play against it.