5 dpo dip?

I'm feeling really anxious this morning! I'm only relatively new to this ttc but already its been so emotional. My cycles have the past 3 months been really long after years of being regular. This was my first month charting and I was beyond worried that I would not ovulate but found all the signs seemed to point to ovulation at around cd30 - cd32. Now I'm on cd 37 and my temp took a big dip! Fertility friend has been unsure about my o date originally marking it as cd 30 but only yesterday it changed its mind to cd 32 but now after this low temp its changed it back. What could a dip this early mean? 
I started to worry last night anyway as my last 2 cycles have been 41 days and I was concerned I would have a short luteal phase. Could this be the cause for the dip?