Congratulations on the pregnancy.

Pregnancy is not the time to make radical changes to your diet - PCOS or not.

Given that you have concieved naturally even with PCOS (many women do - I have 3 times!) and have a BMI of 22, I wouldn't think you need to do anything special except follow a generally healthy diet and take heed of general food safety guidelines for pregnant women.

All the best for the next 32 weeks or so,
TICKLISH