I have "adult onset Tourette's." I have facial tics, hand and arm tics, and make noises. It gets much worse with increases in anxiety, lack of sleep, smoking pot, or drinking moderately a couple of days in a row. Nicotine actually helps a lot, and used to smoke (25 years ago) very heavily. Now I use various replacement products. That used to be an acceptable prescription for it but it seems they switched to other drugs. I find that lifestyle changes are enough to almost completely negate any problems. I can tell when I am getting "that feeling" and if it is mild I can sort of clench my index finger and thumb by tapping and it seems to redirect it somewhere it isn't obvious. I also have the panic attacks and OCD type behaviors.
I take E and depo-provera injections and that doesn't seem to cause any problems. In fact I always sleep better after the E injections and that really helps. What doesn't help are that the males in my family are expected to join one of those hyper masculine, male only secret societies. That produced huge stress and anxiety and lots of tics. For 20 years.
I would try to cut the anxiety as much as possible. Whatever that might entail. Especially if you are overly conscious of it. I make sure I get enough sleep and take naps if I am at a conference of some sort. I also plan to only have a drink or two at one dinner on a multiple day conference. Hope this helps and that you have your own coping mechanisms.
Just reread your post. I think that you will find that it will be a fairly long time before it is obvious from the HRT alone. That gives you, probably, years to figure out your course of action with the child.