Rant!! Sick of being compared to coworker

My manager/coworker is due about a week and a half after me. She is nearly 6ft and a very large gal (near 400lbs). My boss/ the owner of the company keeps comparing us in regard to our work performance during pregnancy. Example: I pee about 6 times in a 9hr shift. I drink a lot of water because my hands and feet get painfully swollen and I get migraines if I don't. My boss started docking my pay about 1hr/week because "_______ doesn't use the rest room that often" I called in for one 4hr Saturday shift because I just really needed the extra rest. This resulted in some major attitude from my boss. I also had a 4 hr friday shift taken from me. She (coworker)came in 4hrs late last Wednesday and my boss was fine with it. She also constantly bitches about back pain...well duh...when you are 200lbs overweight pregnant or not your back will hurt. Also she has gained about 40 visibly with the pregnancy so far. I'm 25 weeks she is a lil over 23. This whole thing makes me want to scream. Just because I don't look tired doesn't mean I'm not. Just because I don't bitch about my back, tailbone and feet doesn't mean they don't hurt. Just because I pee more often than I did before I was pregnant doesn't mean I'm trying to game the system and should be docked pay when noone else is docked for bathroom time.

Ahhhhhh Grrrrrr. Ok rant over. Thanks for reading.