Nursing time change?

Ellie • Engaged to my soulmate💏and newly a SAHM to a 8 year old boy 👶🏽 4 year old girl and my newest baby girl born 1/25/18👶🏽👶🏽🎀🎀 💕

For the last 7 weeks my baby girl has nursed for about 30-40 minutes at a time.. 15-20 per side. She is 2 months old today and for the last 2 days she’s only nurse for 20 minutes at a time.. 10 minutes per side.

Is this normal? Is she getting enough?