Advice please!!

I am 27 years old. I am a bit overweight and my first baby was born in 2012 via c-section so I have a bit of scar tissue from that. Hubby and I are ttc #2 and started in July. I got super excited this cycle because AF was late. Although I had a BFN at 5 days late I was still hopeful because no AF and no symptoms of AF coming. I ended up being 9 days late which is completely rare for me and I am just not sure what could of caused me to be that late. I was not feeling stressed about anything and my cycles are usually 32 days like clock work. The only thing I can think of was that I started working out but not too hard the beginning of July. Does anyone have any advice on to why all of a sudden AF would be so late?