Well you might contact the mermaids, its a group specifically for transgender youth:
mermaidsuk.org.uk
"We offer information, support, friendship and shared experiences."
They can be contacted via mail or phone...
you could ask there for more information and support.
And you might ask a counselor to support you...
and you could have a look here:
https://www.susans.org/forums/index.php/topic,180045.msg1658077.html#msg1658077Its up to you what you say since you know them best...
Well some people compare it to a twin... they will be like their male/female twin, with the same sense of humour...
and some people write a letter...
I'd say take the time you need but keep at it...
hugs