Am I wrong?

So I’ve been at my job going on a year plus now, and since I’ve been working here I’ve been working six days straight. Now that I’m pregnant I’ve been having horrible lower back and leg pains. I kid you not once I get home I can barely walk and once I lay down it so painful to get up. My boyfriend has to physically lift me up. Here’s the kicker I’ve been asking my job since September to at least take a day off of me since I’m pregnant. My job keeps coming up with this excuse that they don’t have anyone to cover me. Wellllll I have a appointment with the high risk doctors on Thursday and i was thinking I should ask the doctor to write me a note to reduce my hours. Am I being petty? Would you do the same thing