Missed ovulation?

My period has always come every 28 days but this month it hasn't, it has been 32 days since my last period. I have taken 3 pregnancy tests and they have all been negative, I am not under any stress, and I am not exercising anymore than I normally do so I am a little confused as to why I haven't gotten my period. The only thing I can figure is I haven't ovulated, does anyone know why that might be? I am a healthy active 28 year old so I can't figure it out.