Thanksgiving rant

I have terrible morning sickness and can only eat small meals but my husband and his family (who do not know yet that I'm pregnant) and my family (who also do not know yet) want me to make all the side dishes and pies...I am so not feeling it this year. I just don't want to slave over a stove for hours when I can only eat a cup size of food without throwing up 😞 how should I tell them without telling them I'm pregnant? I don't want them to think I'm being rude... especially my mother in law.