I'm not an endo and I'm not on HRT yet, but from what I've heard and read 6 months with almost no changes is perfectly normal. Most people that say they changed a lot in three month are delusional because they are in a huge pink fog.
We all react differently to the different drugs, there's our genetic differences and then a lot of outside factors, like our environment, diet, etc. So HRT needs a bit of trial an error. Most people have their dosages changed by their doctors at some point after seeing how the one they prescribed affect all the different levels.
You're not immune to hormones, it's just a process that takes time. And then you have to be realistic with your expectations. Look at the women in your family. How did puberty affect them? I, for example, know that I'm not going to get a lot of fat on my hips and butt, so I'm working on making that area grow with musculature instead (which is a good thing to do here in Brazil, they're really assperts - I mean experts - in that type of workout), while I'm likely going to get a more than decent breast size.