Uncomfortable desk job

I am a little over 25 weeks pregnant with my second and I am incredibly uncomfortable I have a desk job and can find no position that is comfortable! On top of that my maternity jeans have become the devil and are incredibly uncomfortable! Any suggestions on how to get comfortable at a work desk and how to talk to boss about changing dress code for duration of pregnancy? Or any suggestions on jeans or work pants that look professional and are actually comfy! I am struggling here! First pregnancy was nothing like this!