Hey Nic welcome to the forum!
Its always so lovely to meet new people and its great you took the plunge to share your story. I can hear its all still really new to you guys and the reality of it is still sinking in, so thanks for sharing your story with us, its a privalige to hear it.
I think talking about it and meeting others really helps, like you say, to feel less alone in it all...and everyone here knows what HD is which is really unique and special.
In regards to the insurance stuff ...it was an absolute headache when i was doing all that..

.. so i really feel for you going through this process. Noone would insure me initialy, but once i got in contact with a group called IFSA things changed slightly.
here is a link to a discussion we had about insurance a while back...and what happened for me in the end
http://www.hdaustralia.org/viewtopic.php?f=4&t=48 It would be risky not disclosing it, you wouldnt wont to pay into something and feel secure in that and then they pull it out from under you when the time comes that you need it.
It sux though...and it feels like discrimination....and its pretty much the one time someone knows what HD is!! and of all the unhelpful people in the world its the insurance companies!
Im sorry to hear about your mum and brother testing positive...is your mum doing ok? which state do you guys live in?
I hope the process for testing goes smoothly. Its a hard time...and your very brave for facing this disease head on and planning for your life and children. Theres always someone here willing to listen or answer a question or just to be around when you may need it...so welcome!!
Look forward to talking more
Warm Regards
Michelle x