strange period?

Okay for the last 2 periods my periods have been really strange
The 1st on started a bit (really really light) then stopped and started probably 2 days later and only lasted for 5 days (normally mine last a week) 
Then the next one only lasted 5 days but was lighter than usual. 
I've never had sex but have been in contact with sperm before. 
Has anyone else had a similar experience?