When you say your coop is supposed to hold only 30, do you mean the entire coop with run, or just the hen house part of the "coop?" Because you could squeak in a couple extra if you have 10 sq ft per chicken in the run... for 33 that would be 330 square feet. Inside the coop, you need 4 square feet per chicken, BUT some have gone down to 3 square feet in the coop "hen house" portion. Have you got at least 330 square feet in the run? That would be width times depth, say 10 by 33 feet, or any combination that works out to 330 square feet.
If you have enough or more than enough space in the run, you CAN "squeak" a couple more in the coop IF it's a mild weather area, and there will never be an extended period of time they are enclosed INSIDE in the coop together (like for months when it snows or a full week when it rains, etc.).
Hope that helps.