Measuring different

Okay so my periods have been super irregular since having my first daughter a year ago. I just found out I was pregnant with baby number 2 and my last period was in Feb and so I was supposed to be around 10 weeks, but I'm showing 5 weeks 2 days. My question is since my periods were so irregular is it possible I just ovulated later? Anyone else have this issue as well? I'd greatly appreciate any feedback