Nursing Less

My baby is now 6 months old and I am exclusively breastfeeding although I introduced purées at 5 months as recommended by the pediatrician due to some stomach issues. (The solids do not take the place of a nursing session).

He used to nurse anywhere from 10-12 minutes per session but now seems to nurse 5-7 minutes per session. Has this happened to anyone else around this age?

He seems to be wetting diapers and gaining weight, but it still concerns me.

Thank you ladies!