After frozen embryo transfer

Nals • TTC #1 IVF 💉 , 👼🏻 2.3.20، 👼🏻👼🏻 16.5.20، 👼🏻 2.9.20, 👧🏻 23.3.21

I transferred Day 5, 2 frozen embryos on May 3rd at 11AM, when i woke up next day i feel very tightness on my pelvic like a mild cramps, so i googled what happens and saw this,

Now May 4th should i count my self as Day 1 or Day 2?