Can breastfeeding mess up me cycle after it returned??

So my son is 6 months old and I’m breastfeeding.. trying to interpose solids but he is not impressed and just loves his boob time. 😂😂

To my surprise my period returned when I was 5 month pp (May 8th) and we decided to ttc again so I monitored my ovulation with checking my cm and I used clear blue advance digital and I got a peak may 20th (never got a high fertility just low and then peak).

I was expecting my period now last Friday but still now sign of my period so I’m 2 days late. Put still just BFN.

Can I expect my period being late because I’m breastfeeding or?? And also maybe a stupid question can breastfeeding cause a false negative???