Glad to hear your doing so well and helping others.
Travel insurance is one of the painful things we have to deal with post transplant. Especially if traveling to the US. Example I've just booked a trip to Mexico for 3 weeks and I was able to get cover but it's costing me $1650 and my wife who is traveling with me is only up for $189.
Insure and go are always my first choice. However they don't cover to the US if you have had a transplant. I am pretty sure they cover everywhere else.
They have another company under their umbrella called " All Clear Travel Insurance" they are the ones that have covered me but its expensive.
QBE said they would cover me but after someone from the transplant team filled in a form to say I was fit to travel. I did this however they would only cover me for $100,000 for about $400
but in the US $100,000 won't get you very far if something does go wrong.
The other company ive used in the passed was COVERMORE but I think at the moment they have stopped insuring transplant patients.
They quite often change but this advice is current for 2018.