I was on crutches for the last 5 weeks of my pregnancy.
I ended up leaving work at 36 weeks, I really couldnt handle the commute. I was already doing shorter days so I could miss rush hour and guareentee a seat on the train and tube.
so I stayed at home alot, but I could get away with them for a short walk, but I did suffer.
Try and put up with them though as you still have a way to go, my SPD only got worse.
Sorry its hard!!