What going in can anyone shed light

So My cycle is usually anywhere from 28 to 30 days the last 2 cycle I been tracking ovulation and getting positive test some where between the cycle days of 20 to 25 day which i would think is abit late the last 2 cycle have been delayed but not by much just 2 days but based on where I ovulate I should be delayed by like a whole week if not more so can someone tell me am I missing something should I get some bloods done to see my hormone levels cos it seem to me that although I ovulating even though it may be late I don't have the full to weeks after ovulation I only have a week and then my period comes so is there something my body not doing and because I been symtoms spotting I always think I may be pregnant which is so annoying cos then flow arrives