When am I due?

Lee • Mommy to 3 year old girl! Baby #2 joining us March 2016!!!
I've had irregular periods since getting off the pill! My last period started Aug 17. I had spotting on Sept 18 (I think related to ovulation)! I got my last BFN Oct 1 and my first BFP Oct 4!!! My Dr. doesn't want me to come in until the end if Oct (otherwise I'd just ask her). Some of you ladies seem to have a PhD in fertility.....so when would you estimate I am due?