HRT dosage depends upon the person. I was never on more than 1/2 of a full dose, and still had mega breast development (I remember my doctor back in 2002 making the mistake of asking me when I had had breast augmentation surgery - when I informed him I had not had BA, he informed me that I had major breast development). Physical feminization from HRT is dependent upon how many estrogen receptors your body has. In some ways that is just as important as doseage. Remember, any estrogen that doesn't latch onto receptors, ends up just getting metabolized by your liver. Testosterone suppression also helps things (things really really took off after my orchie [you know, as of this week, that happened 17 years ago, I'd almost forgotten that!]).
A few years after SRS, there is no need IMO for a full dose of HRT daily (I'm only on 1/3 of a full dose). Why? To help minimize breast cancer concerns. That may not be a concern for you, but it definitely is for me. My sister ended up having a double mastectomy 10 years ago due to breast cancer, and when I informed the mammogram technician of this during my annual mammogram (you're asked about any family history breast cancer, when you go for a mammogram [a mammogram is something which any MTF on HRT long term SHOULD be having done yearly of you're 40 years old or older]), this became a part of my medical file as a potential medical concern for me. Since many breast cancers are estrogen linked (my sister's was), the more estrogen you have, the higher the risk of estrogen linked breast cancers.