How long does your baby nurse for?

Im pretty sure Im an oversupplier. My daughter is 4 weeks and usually only nursed for about 10 minutes on one side before being done. If I can get her to nurse on both sides for 20 minutes total it feels like a small victory for me. Past few days she's only been nursing about 7-8 minutes a side & that's with her pulling away from the breast every 30 seconds or so. She nurses about every 1 & 1/2 to 2 hours during the day.

She has on average 5 wet, 2 dirty & 2 mixed diapers a day but I'm still worried shes not eating enough.