Sweetie, don't blame the hormones, that kind of environment would make me go mad even if I wasn't pregnant. If you have so much experience I'm sure you'll find some other job in which they will treat you normally.
Everyone needs respect in their work place and being pregnant should give you even more and not taking it away by comparing you to another pregnant woman (mostly when every pregnancy is different, even the same woman can have different symptoms when they get pregnant again). So this shows their great ignorance.
I would try to find another job, the environment will damage you and baby too. And that HR person sucks too, because it's her only job to maintain a good environment!