694 day's later and still no period

My son will be 15 months on the 30th whom I'm still nursing 5+ times a day. My husband and I had a conversation and would like to try for our 3rd how can I successfully become pregnant with no cycle to track? I only had the after birth bleeding other than that I haven't had a cycle since a month before finding out I was pregnant almost 2 year's ago. I'm not on birth control and we do not wear condoms we usually have intimacy 1 to 7 times a week depending on how tired we are. Any advice will be greatly appreciated!