Breastfeed causing so much stress.

My lo is 4 and a half months old, and he has started only feeding for 3-4 min during the day, and goes a long while between feeds. He does feed for longer before bed and during the night. He is having significantly less wet nappy’s/diapers than he used too, which aren’t really heavy either. We have had thrush multiple times, which is currently not an issue, so I don’t know what’s going on. It’s causing me untold stress and anxiety as I don’t know if he’s really getting anything during the day. I don’t know what to do but I must do something soon as it’s making me ever so unwell. Any advice? Thank you.