Breastfeeding and ttc..

My son turned one on November 26th. I am still currently breastfeeding but attempting to wean him. He nurses maybe once during the day but he nurses a lot more at night. I got my first period since having him in July, then missed my period in August and September. I got my period in October and November and I was on and off taking ovulation tests and none seemed to show positive until 2 weeks ago (the week before I got my period). I am just currently ending my period today. My husband and I have 4 children and we are looking forward to adding our last and final baby to the bunch. What are my odds of getting prego while nursing my one year old? Has anyone had any luck getting prego while nursing? I didn't get pregnant with my 4th while nursing my 3rd but we were not trying at the time. We are so anxious for baby #5!