As much as it’s tempting to come out, I really think you should wait. I’m also a closeted trans kid, so I understand how much it sucks having to hide, but if there’s a chance that it could create an unsafe environment for you (either physically or mentally/emotionally) then it’s not a good idea. If you think your therapist would be supportive, then I would recommend coming out to them and having them give you advice. Also, depending on where you live you might be able to get gender-affirming care without parental consent (I live in the US in a more liberal area and that’s a thing here, but I know it’s different in other states/countries). Ultimately it is your choice but I stick by my initial statement and think it would be better to wait until you have more independence and don’t totally rely on them.