Avoiding pregnancy

My fiancé and I had sex the last day of my period in August. August 29th. I haven't had my period in sept. According to this app i'm 3 weeks late. But according to my old period tracker app (that has a lot more of my data on there) it says I'm only 6 days late. I have an irregular cycle. I took two tests one on sept 19th and one on the 26th both early in the morning and they both said neg. I also have polycystic ovarian syndrome. (Cyst on the ovaries that cause infertility). I always have a clear white discharge leaking out of my vagina. It soaks my underwear. Could I be pregnant? Please help.