Lovely performance, thanks for sharing! Sitting down to play is not my personal preference either, I much prefer standing up to play. There are a couple things to keep in mind that might make it more satisfying for you. Try sitting on the front half of the chair, making sure to sit up nice and tall. I like to tuck my right foot/leg down and back to get my right knee out of the way of the bow hand.
Suzanne from Violin Tutor Pro