Unprotected sex postpartum

DH and I had sex last night at 5 weeks post partum and did not use protection. You can't get pregnant that soon right? My lochia stopped three days ago. Oh and it hurt! I had a small tear during delivery but I thought it was healed. I won't be trying sex again for awhile. Yea I know I should have waited! Now I'm just worried I could get pregnant again. Should I get the morning after pill?