Hi I Have Recently Come Off The Pill - This

Hi I have recently come off the pill - this is the 3rd period since coming off the pill. The first took 33 days lasted 6 days the second was 38 days and lasted 6 days and this period came after 29 days but has only lasted 3 days. Should I be concerned that I have irregular cycle? I am trying to become pregnant and want the best chance possible but this has kind of thrown me to only have a short period, this has never happened even before going on the pill.