Advise Please

One app I use says I'm 16dpo and GLoW says I'm 10dpo.  I'm not sure which to believe as I can't tell when I ovulate. I have had some symptoms this cycle such as a cold at 3dpo (according to my other app), canker sore, cramps, back aches and feeling very tired.  I'm not sure when to test.  My cycles are a little irregular ( 28-35 days). I am currently on 29. Any advise would help.