Hi Rava
I can't (and won't) comment on dosage, partly because I take pills and so don't know what the injectable equivalent is, and partly because the board rules don't permit such details to be posted or discussed.
But in general terms, postop you will need at least some level of HRT FOR LIFE! That's because unlike a menopausal natal woman you now have very little ability to produce your own sex hormones. Failure to maintain at least a basic dose longterm will almost certainly result in crippling osteoporosis and could also contribute to other serious medical problems.
I know of several people who tried to do without hormones for various reasons. All have lived to regret it and are now back on at least a minimal dosage of hormones.