Ask yourself a question. Veganism often runs alongside ideas like conservation, recycling and sustainability. For me things like recycling, and more importantly reuse and sustainability are more important. As is saving the planet and looking after my own health. After all, if I'm not here, I can't do much or make any difference.
So sitting on the floor, it's all great whilst you are young enough and able. And I did for decades by choice but only because I found it more comfortable than a sofa (I found out why just over 2 years ago when I became permanently disabled) but there comes a line drawn in the sand where recycling and sustainability meet veganism and you need to decide which side you are standing or sitting on.
Personally I'm on the former. I refuse to throw away perfectly good woollen clothing decades old just because it doesn't meet with the concept of veganism. Continuing to use it, reuse wool in blankets (yarn often comes from petroleum based products anyway and I would rather wool decades old than petroleum or petrochemical products), old leather or suede items I had previously, items such as carpets etc is far more environmentally friendly than any other option.
Plus you need to decide where that line is drawn for other ideas. Paint on walls (petrochemical) , floor wood varnish (bees wax or petrochemical), cars or public transport (just take your pick), medication (anything from petrochemical to animal products), colours (anything...) all of these items either are non-vegan or don't support an environmentally friendly lifestyle. Afterall, veganism isn't just being kinder to animal (animal welfare features highly), it's a more sustainable lifestyle and that includes things like not flying unnecessarily and pursuing a more sustainable lifestyle.
So, next time the sofa needs replacing, considering something with cotton, bamboo, hemp, linen or some other plant made covers, but don't forfeit your health to get to that point.