Hi @Rainbowhairdontcare!
I'm 1.5 weeks off my maternity and I have been feeling the exact same with regards to productivity and being uncomfortable!
Do you have a desk job? If so, me too and I find that comfort-wise, pillows and finding something to put your feet on helps. I also take five minutes every now and then to sit back on my chair for a bit as, my peanut doesn't appreciate the lack of space when I am hunched over my keyboard and tends attempt to push me back upright all day long!
I have found myself making a lot of baby-related spreadsheets instead of doing my work because, I have passed 99% of my tasks over now so, I actually don't have much to do, which can make the day drag a bit.
Like you though, I was determined to keep on at work as long as possible as, I only qualify for statutory maternity pay and I want to take a year off so, I'd rather make sure I'm earning for as long as possible before then!
Tips for making it bearable... Sorry, I don't really have any! The days are dragging but, honestly the weeks are flying by. All I have done is taken to making spreadsheets/checklists, Googling baby/pregnancy related stuff and stalking Mumsnet, instead of working but, that's probably not the best advice 
Sorry I couldn't be more help but, I promise you will be at 37 weeks and counting down the days like me, in no time!!
Congrats and good luck! Xx