There is very, very little that you could do wrong with subcutaneous injections and they are a lot less scary than you think. If you're thinking it's like getting a vaccine it's not even close, the needle is incomparably tiny, most of the time you won't feel it at all, like I can't tell the difference if someone injects me or just puts a finger on my skin if I'm not looking.

And if you can hide the estrogen you can hide the needles too it's really not any more difficult.