I had to reread the year and a half part- I'm impressed!
This may just be my training, but I'd like to see you lift your hands a little when you jump, or put them a little forward. The horse you're riding seems a tiny bit upset that she doesn't have her head. In addition, you make a mistake that I made for a long time. Stay in your jumping position a little longer than you think you have to, before and after. Unless your horse is being naughty and pulling out of the jump, this is generally more comfortable for them. Its easy to fall into the habit of sitting down as soon as you feel your horse land, but usually only their front feet have landed.
I'm stunned, though. A year and a half into riding and I hadn't even thought of cantering!