Anyone measuring small??

Kennedy β€’ Engaged to my soulmate! Gave birth to our little boy Kayden Kristopher 02.22.2016πŸ‘ΆπŸ’™ Took 13 months of TTC with PCOSπŸ’• TTC baby #2 started August 2018πŸ’–

So according to my date of ovulation I should be 7 weeks 5 days pregnant.

But when I saw my doctor they said I was only measuring 6 weeks 3 days. I'm a little concerned but they said everything was fine. Has anyone else experienced this??