Desk job + 26 weeks = uncomfortable...

Does anyone else have a desk job and finding it hard to sit comfortably? Everytime i sit up straight at the desk i feel like my baby is telling me to move... He's constantly kicking and jigging around. The only relief i get is if i lean back and streatch out slightly.. and even then he's not happy... my shifts are 12hrs long and im finding it an effort to get through to my breaks..