7days late confused help...

Im so confused Im 7 days late today i have a 22 day cycle so it says on my calendar I took a test its negative im confused cause I was going through my period cycles from March an there all different march I had a 23 day cyle, April I had a 20day cycle,may I had a 21 day cycle, june I came on twice first cycle was 24 day an second one was 25 day cycle then july I had a 19 day cycle then August I have 22day cycle my last period was 7th aug to the 12th August an was due back on the 28th of august but nothing yet....HELP