HELP!!??

Heather

Question, long story short I have never gone on birth control. I have a 9 year old son and never actually 'tried' to get prego again but I'm now 29 and have baby fever like crazy. I have been checking my ovulation the last 2 months and last month it went from low to peak the next day. I checked yesterday and it went from high back to low today. no peak time Does anyone know Why? did I miss my ovulation for the month. Tia.