Yeah it's very possible. There's a doctor in Phoenix, I know of, who does this. He feels that shot-gunning, as he terms it, makes the sound of trans guys voices less good and pinched. There is a guy on youtube named Yanin who did this. He transitioned over something like 4 years. If you did a low enough dose you might not transition. I think there are genderqueer people who only go on very teensy doses, but it is my understanding that whatever changes you would make on T you will eventually make. It is just time.
But I have my doubts about keeping that much from your parents. I think it would theoretically be easiest on compounded cream as there are no needles to deal with, just a jar and measuring spoon. It would also be super easy to get a very low dose. The stuff has minimal smell. It takes about 2-4 minutes to dry. I think it is less messy than the gel since it takes less. It is more expensive than shots, but a jar that costs me $85 would maybe last 6 months on low dose. They also might get upset re routine changes such as taking a LONG time after your shower.
What about minor changes-- what if you start getting raspy throat. Will they be nagging you about going to the doctor and so on. My thinking is that they will consider changes indicative of a hormone disorder.
So I don't know about it. Sounds hard. But I think it might be theoretically, at least, possible. Small dose T might help you feel better. OTOH, might just annoy you more as your changes will be so slow.
--Jay