Mind games

Had my son July 16th and got birth control a few days after the start of September. I got nuvaring. So I wore it for the 3 weeks and took it out well my husband came inside of me on my off week a few days ago. This was my first month back on bc. Well time came to put In a new one and I did. Now my body hurts I'm tired and feel like I'm starving to death. I formula feed so it can't be from producing milk. Any way my mind keeps saying pregnant and im like can't be I never am when I think I am. Just keep telling myself I'm tired and hurting from working 6 days a week and am starving because my food svhedule was thrown off ay work.