cycle buddy? AF due 3/31

Jessica
Hello my name is Jessica. I'm 26 and TTC #2. I haven't been on birth control since September 4, 2013 (that's when my IUD was up.) my husband and I haven't been trying too hard but I am ready to kick it into high gear and make a more valiant effort. My husband and I have wanted a baby for a couple years now. My AF usually lasts 4 days but has been kinda irregular. The my cycle length is 28 days. Cycle buddy anyone?