I did transfer on 16may. My bhcg on 28 was 528.Yesterday I went to my doc appointment he said that my 2 bb are same size. I need to know what week am i.?

Congrat/Confirm w/OB. The date (and hour) of conception should be known by the fertility doctor. That can be used by fertility, OB and peri and neonatology doctors to determine the gestational age (ga) and due date. As a maternal-fetal medicine specialist, i know how important it is for all to agree on one estimated date of delivery (edd). Therefore, i will only give approximate ga for the babies as 8-9 weeks on july 1.
Unclear. I would probably recommend asking your doctor. I don't know what 2 bb means.