My daughter is 15 weeks and EBF.
She goes to bed at around 8/830pm and will sleep until 2 - 3 am (usually a 6 hour stretch); then she wakes again around 5:30/6am, feeds, and will sleep until 8:30/9am.
Typically regardless of when she goes down it is -
6 hour initial strecth
2.5 hour strecth
2 - 3 hour strecth
What are your babies doing? I am wondering when or how the 6 hour stretch will get longer.