I keep hearing comments like "It's not an illness, you're just pregnant" - just getting to me at the moment.
Hello, That sort of attitude is not only unhelpful it also possibly verges on the boundary of harrassment. Is there someone at work (in a position of authority) who is a mentor or ally for you? If so, perhaps confide in them and find out if they have some suggestions for tackling this situation. If not, your workplace may have diversity support ppl, might be worth having a chat to one of them. Of course you need to take care of yourself, that might mean reducing your hours in the short term, pulling a sicky or two (any doctor who hears how stressed you are will happily write a certificate) and requiring the workplace to meet your needs for a bit.

I really hope this situation improves for you, please don't blame yourself, and yes pregnancy is hard work too (think of it this way - you're currently holding down two jobs !