Line progression

Brittanie

I clearly see the line progression on the first signals from CD 26 (11/12 dpo) to CD 28 (13/14 dpo) but I’m concerned with the progression on the frer from CD 28 to CD 30 (15/16 dpo) I think they look the same.

Any input? I go back for my second beta tomorrow. My beta on CD 27 (12/13 dpo) was 28.