If someone is worried or stressed that they may be pregnant, could that make my body act a certain way?

Yes!: Don't stress needlessly. Get a home pregnancy test and find out. If you are a week late the results should be reliable. If you aren't sure, you doctor can confirm with blood tests.

Stress is a mess: Stress can cause many symptoms and health problems. I would recommend that you get in and have a pregnancy test done - then you do not have to worry about it anymore.