Pregnancy doctors note?

Taylor
I work at a coffee shop/cafe, and they are asking me for a letter from my doctor (also needed if I want to apply for disability) with my "restrictions." I am healthy and a low risk pregnancy, so my doctor didn't give me any. But at work I can't work on food because the smells kill me and morning sickness is bad enough as it is, and I take an extra break each shift because being on my feet for 3+ hours causes back pain and slight cramping. Idk how to ask for a doctors note saying these things, aren't they just routine pregnancy symptoms? Has anyone else asked their doctor for this?