I had sex 10 days after my period ended, i took plan b 1 hour after the sex and i have about a 37 day cycle. what is the likelihood of pregnancy?

Very low, not zero: Assuming a cycle length of about 6 days, you had intercourse very close to when you were going to ovulate based on your cycle length. You also took planb appropriately, and it has a very high likelihood of preventing pregnancy. I would say that your chances of pregnancy are <5%. You need to take a pregnancy test 2-3 weeks after this episode of intercourse to rule out pregnancy.