Elaina thank you very much for your insightful reply.
I did in fact book my flights, the day after posting the OP. My partner kept suggesting I just drop in to our local travel agent and talk to them and, as I sometimes do, I actually listened to her. They made it very easy. I probably could have done it myself online but this way I got to ask questions and I felt looked after and helped.
For the flight back I paid extra to reserve a seat and secured a bulkhead aisle seat (right at the front of the plane). The agent said they generally have lots of leg room and are really nice seats, and they are close to washrooms. And there is no one in front of you reclining into your swollen lap lol.
Of course it could mean that I'll be in the thick of the action if there is trouble in the cockpit, but after GRS I'm sure I will be able to handle pretty much anything.
My partner has knee issues right now too, and moreover she is a cancer survivor who gets easily overwhelmed by stress and fatigue, so we agreed it was better she stay home and look after the house and our pets. If she came I'd be expending energy worrying about her. So my younger brother was supposed to try and come. But he won't be able to afford it and I can't help pay his way myself. After I booked the flight I sent him a message telling him the exact costs and he wrote back very apologetic and feeling bad about not being able to be there for me. He even signed his message "your (super proud of his sister) little brother". He's so sweet! Hard to believe he used to want to kill me before. He's been my biggest supporter.
But you know, you're right. There is something about doing this alone that appeals to me. It does feel like that is a better path for me, and I do have confidence the airline and everyone else will look after me. The clinic does pick up people at the airport and take you back out there. I am thinking of going in a few days early anyway to spend some alone time in Montreal. I am so very rarely alone these days and I think it will be good for me to focus on my journey. Hopefully I won't be too nervous to enjoy myself a bit! I'll also be about 3 weeks sans hormones so watch out Montreal lol.
That's a great idea about the wheelchair and the note. I asked the agent and she thought it was only necessary (the note) if I needed special services, but suggested I get one anyway. I think that would be prudent, as would be booking a wheelchair ahead of time. Thanks for the suggestion.

Bree... I got your message but I can't reply I don't think. How many posts do I need until I am someone around here lol?