BBT & Ovulation confusion

Caroline
Hello everyone,
​I'm new to this app and TTC at 36 yrs
​Having entered all my info it tells me my most fertile days been from the 23rd August when my period ended for 3 days. The bbt however shows a spike on the 19th when I was bleeding and low readings over the most fertile period. I'm confused!!
​I also saw my doctor this week as I'm concerned over my age and she told me to chk the ovulation tests about a week after my bleed but looking at the chart I've already missed my change for August 
​Anyone help and advice me?
​Thanks x