Hi..I used to sew at my daughters desk but it was so uncomfortable...not only did my back hurt but I started getting pain in my neck....I now have a proper work surface and a height adjustable chair (cheap from Ikea) that has a back support....Now I get No back pain ....please don't continue , you could really suffer in the future. Go and test good chairs out and takes lots of breaks..Also make sure your foot pedal is at the right height, putting it on a phone directory can make a real difference....even set an alarm every hour and walk round the house.....that's the nurse in me speaking