Labor Pains?!

I'm 38w4d and 2cm dialated as of two days ago. I worked a full day today (hairstylist on my feet for 10 hours) and throughout the day have had sharp, painful contractions but not regular enough to time. Baby boy is still moving around like crazy but as I am laying here in bed the sharp pains are getting more regular. No actual signs of labor... no loss of mucus plug just spotting after my cervix check two days ago. How do I know if I'm actually in labor? My coworker went into labor at work but said it just felt like period cramps and by the time she got to the hospital, she was 7cm!!