Just bring one in. If they say anything about it, take it back home.
It couldn't hurt.
They should provide one anyway, but if you afraid to ask, just bring your own.
I would look for a nice desk job that involves a comfy chair. Doctor office, something like that.
But since you are pregnant, you might just want to tough it out where you already work because this will give you more work experience, better resume, etc.
Once you have the baby and are ready to go back to work, then look for a new one.