Eating ... Ebf

My ebf baby is 7 weeks old and I've been noticing shorter feeding times with her this week. She used to eat for about 15-20 mins and sometimes take a little more after a 5-10 min break. Now she seems to be eating for only about 5 mins and sometimes will go back on for another few after a break (gassy).

I know I have a fast let down so I thought she kept popping off because of that but when I put her back on she'll eat for 20 seconds and come off again like she is full.

Is it possible that she just doesn't need to eat as long? Her output seems about the same to me, I usually change her 9 times in a 12 hour period.

I'm block feeding because of my letdown, is that maybe contributing?