Preterm labor?

I'm now 33 weeks and I begin to have very strong contractions. Immediately I went to the doctor they picked up my very strong contractions chose not to stop them due to the fetal fidronectin test which came back negative and also because my cervix wasn't dilated. I'm still having these strong contractions. Could I still be in preterm labor even with a negative FFN test? & has anyone got s negative and still delivered within the 3 week period?